Sirius International Insurance 10-Q 13 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Document and Entity Information
Entity Registrant Name	Sirius International Insurance Group, Ltd.
Entity Central Index Key	0001744894
Document Type	10-Q
Document Period End Date	Mar. 31, 2020
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		115,299,341
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets
Fixed maturity investments, trading, at fair value (Amortized cost 2020: $1,705.0; 2019: $1,656.6)	$ 1,732.1	$ 1,681
Short-term investments, at fair value (Amortized cost 2020: $1,032.7; 2019: $1,090.8)	1,041.8	1,085.2
Equity securities, trading, at fair value (Cost 2020: $409.5; 2019: $379.2)	366.6	405.2
Other long-term investments, at fair value (Cost 2020: $323.2; 2019: $315.4)	355.5	346.8
Cash	140.5	136.3
Restricted cash	15.3	14.3
Total investments and cash	3,651.8	3,668.8
Accrued investment income	10.9	11.2
Insurance and reinsurance premiums receivable	964.2	730.1
Reinsurance recoverable on unpaid losses	444.2	410.3
Reinsurance recoverable on paid losses	85.7	73.9
Funds held by ceding companies	260.5	293.9
Ceded unearned insurance and reinsurance premiums	245.5	162
Deferred acquisition costs	168.2	148.2
Deferred tax asset	171	166.7
Accounts receivable on unsettled investment sales	35.2	6.7
Goodwill	400.8	400.8
Intangible assets	175.9	179.8
Other assets	143.7	161.4
Total assets	6,757.6	6,413.8
Liabilities
Loss and loss adjustment expense reserves	2,519.6	2,331.5
Unearned insurance and reinsurance premiums	979.2	708
Ceded reinsurance payable	332.8	244.7
Funds held under reinsurance treaties	148	169.1
Deferred tax liability	183.5	205.9
Debt	664.8	685.2
Accounts payable on unsettled investment purchases	53	2.3
Other liabilities	200.4	201.3
Total liabilities	5,081.3	4,548
Commitments and contingencies (see Note 19)
Mezzanine equity
Series B preference shares	199.6	223
Common shareholders' equity
Common shares (shares issued and outstanding, 2020 & 2019: 115,299,341)	1.2	1.2
Additional paid-in surplus	1,100.1	1,098.2
Retained earnings	673.7	778.5
Accumulated other comprehensive (loss)	(300.9)	(237.5)
Total common shareholders' equity	1,474.1	1,640.4
Non-controlling interests	2.6	2.4
Total equity	1,476.7	1,642.8
Total liabilities, mezzanine equity, and equity	$ 6,757.6	$ 6,413.8

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fixed maturity investments, trading, amortized cost	$ 1,705	$ 1,656.6
Short-term investments, amortized cost	1,032.7	1,090.8
Equity securities, at cost	409.5	379.2
Other long-term investments, cost	$ 323.2	$ 315.4
Shares issued (in shares)	115,299,341	115,299,341
Shares outstanding (in shares)	115,299,341	115,299,341

Consolidated Statements of (Los

Consolidated Statements of (Loss) Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues
Net earned insurance and reinsurance premiums	$ 434.7	$ 311.9
Net investment income	13.5	20.1
Net realized investment gains	20.3	9
Net unrealized investment (losses) gains	(43.8)	74
Net foreign exchange gains	18.5	5.1
Other revenue	4.3	19.6
Total revenues	447.5	439.7
Expenses
Loss and loss adjustment expenses	427.1	183.9
Insurance and reinsurance acquisition expenses	74.7	63.3
Other underwriting expenses	38	35.3
General and administrative expenses	32.1	24.4
Intangible asset amortization expenses	3.9	3.9
Interest expense on debt	7.8	7.6
Total expenses	583.6	318.4
Pre-tax (loss) income	(136.1)	121.3
Income tax benefit (expense)	14.8	(17.2)
Net (loss) income	(121.3)	104.1
Income attributable to non-controlling interests	(0.2)	(0.4)
(Loss) income attributable to Sirius Group	(121.5)	103.7
Change in carrying value of Series B preference shares	23.4	(8.4)
Net (loss) income attributable to Sirius Group's common shareholders	$ (98.1)	$ 95.3
Net (loss) income per common share and common share equivalent
Basic earnings per common share and common share equivalent (in usd per share)	$ (0.85)	$ 0.75
Diluted earnings per common share and common share equivalent (in usd per share)	$ (0.96)	$ 0.74
Weighted average number of common shares and common share equivalents outstanding:
Basic weighted average number of common shares and common share equivalents outstanding (in shares)	115,262,302	115,182,331
Diluted weighted average number of common shares and common share equivalents outstanding (in shares)	127,163,972	127,335,314

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Comprehensive (loss) income
Net (loss) income	$ (121.3)	$ 104.1
Other comprehensive (loss)
Change in foreign currency translation, net of tax	(63.4)	(27.8)
Total other comprehensive (loss)	(63.4)	(27.8)
Comprehensive (loss) income	(184.7)	76.3
Income attributable to non-controlling interests	(0.2)	(0.4)
Comprehensive (loss) income attributable to Sirius Group	$ (184.9)	$ 75.9

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common shares	Additional paid-in surplus	Retained earnings	Accumulated other comprehensive (loss)	Parent	Noncontrolling Interest
Beginning balance at Dec. 31, 2018		$ 1.2	$ 1,089.1	$ 816.6	$ (202.4)
Changes in common shareholders' equity
Share-based compensation			1.2
Other, net			(0.1)
Net (loss) income	$ 104.1			104.1
Income attributable to non-controlling interests	(0.4)			(0.4)
Change in carrying value of Series B preference shares				(8.4)
Other, net				(0.1)
Change in foreign currency translation, net of tax	(27.8)				(27.8)
Ending balance at Mar. 31, 2019	1,775.2		1,090.2	911.8	(230.2)	$ 1,773	$ 2.2
Beginning balance at Dec. 31, 2019		$ 1.2	1,098.2	778.5	(237.5)
Changes in common shareholders' equity
Share-based compensation			1.9
Other, net			0
Net (loss) income	(121.3)			(121.3)
Income attributable to non-controlling interests	(0.2)			(0.2)
Change in carrying value of Series B preference shares				23.4
Other, net				0.1
Change in foreign currency translation, net of tax	(63.4)				(63.4)
Ending balance at Mar. 31, 2020	$ 1,476.7		$ 1,100.1	$ 673.7	$ (300.9)	$ 1,474.1	$ 2.6

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operations:
Net (loss) income	$ (121.3)	$ 104.1
Adjustments to reconcile net income to net cash provided from operations:
Net realized and unrealized investment losses (gains)	23.5	(83)
Amortization of premium on fixed maturity investments	0.4	(0.8)
Amortization of intangible assets	3.9	3.9
Depreciation and other amortization	1.7	2.2
Share-based compensation	1.9	1.2
Other operating items:
Net change in loss and loss adjustment expense reserves	278.6	(1.1)
Net change in reinsurance recoverable on paid and unpaid losses	(91.1)	(8.7)
Net change in funds held by ceding companies	22.5	(20.1)
Net change in unearned insurance and reinsurance premiums	309.5	232.4
Net change in ceded reinsurance payable	111.3	37.7
Net change in ceded unearned insurance and reinsurance premiums	(96.6)	(47.6)
Net change in insurance and reinsurance premiums receivable	(280.5)	(208.8)
Net change in deferred acquisition costs	(26.4)	(14.2)
Net change in funds held under reinsurance treaties	(12.7)	15.4
Net change in current and deferred income taxes, net	(11.5)	9.1
Net change in other assets and liabilities, net	2	2.9
Net cash provided from operations	115.2	24.6
Cash flows from investing activities:
Net change in short-term investments	33.8	(120.1)
Sales of fixed maturities and convertible fixed maturity investments	99.3	135.1
Maturities, calls, and paydowns of fixed maturity and convertible fixed maturity investments	62	59.3
Sales of common equity securities	205	45.9
Distributions, redemptions, and maturities of other long-term investments	7.4	15.3
Return of principal on loan participations	0.1	0
Contributions to other long-term investments	(17.6)	(25)
Purchases of common equity securities	(253.6)	(39.8)
Purchases of fixed maturities and convertible fixed maturity investments	(261.2)	(105.1)
Net change in unsettled investment purchases and sales	22.5	10
Other, net	(0.4)	0.3
Net cash (used for) investing activities	(102.7)	(24.1)
Cash flows from financing activities:
Change in collateral held on Interest Rate Cap	0	(0.1)
Net cash (used for) from financing activities	0	(0.1)
Effect of exchange rate changes on cash	(7.3)	(3.6)
Net increase (decrease) in cash during period	5.2	(3.2)
Cash and restricted cash balance at beginning of period	150.6	132.2
Cash and restricted cash balance at end of period	$ 155.8	$ 129

General

General	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General Sirius International Insurance Group, Ltd. ("the Company") is a Bermuda exempted company that provides multi-line insurance and reinsurance on a worldwide basis through its subsidiaries (collectively with the Company, "Sirius Group").

Summary of significant accounti

Summary of significant accounting policies	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies Basis of presentation The accompanying Unaudited Consolidated Financial Statements at March 31, 2020 , have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") and the rules and regulations of the U.S. Securities and Exchange Commission ("SEC") for interim financial information. The accompanying Unaudited Consolidated Financial Statements present the consolidated results of operations, financial condition, and cash flows of the Company and its subsidiaries and those entities in which the Company has control and a majority economic interest as well as those variable interest entities ("VIEs") that meet the requirements for consolidation. All significant intercompany transactions have been eliminated in consolidation. These Unaudited Consolidated Financial Statements do not include all disclosures normally included in annual financial statements prepared in accordance with GAAP and should be read in conjunction with the Audited Consolidated Financial Statements and the related notes for the year ended December 31, 2019 . The consolidated financial information as of December 31, 2019 included herein has been derived from the Audited Consolidated Financial Statements as of December 31, 2019 . Effective January 1, 2020, the Company changed its reportable segments. The change in reportable segments had no impact on the Company’s historical consolidated financial positions, results of operations or cash flows as previously reported. Where applicable, all prior periods presented have been revised to conform to this new presentation. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. In the opinion of management, the accompanying Unaudited Consolidated Financial Statements reflect all adjustments (consisting of normally recurring accruals) necessary for a fair statement of results on an interim basis. Tabular dollar amounts are in millions, with the exception of share and per share amounts. All amounts are reported in U.S. dollars, except where noted otherwise. Recently adopted changes in accounting principles Credit losses Effective January 1, 2020, Sirius Group adopted Accounting Standards Update ("ASU") 2016-13, Measurement of Credit Losses on Financial Instruments (ASC 326), which establishes new guidance for the recognition of credit losses for financial assets measured at amortized cost ("current expected credit losses" or "CECL"). The guidance applies to financial assets that have the contractual right to receive cash, including reinsurance receivables and recoverables and requires reporting entities to estimate the credit losses expected over the life of a credit exposure using historical information, current information and reasonable and supportable forecasts that affect the collectability of the financial asset. The expected credit losses, and subsequent adjustments to such losses, are recorded through an allowance account that is deducted from the amortized cost basis of the financial asset, with the net carrying value of the financial asset presented on the consolidated balance sheet at the amount expected to be collected. Sirius Group adopted the new guidance using a modified retrospective transition method through a cumulative-effect adjustment to retained earnings. As a result of the adoption of the new guidance, Sirius Group estimated a total CECL allowance of $ 14.9 million. The adoption of this guidance did not materially impact our results of operations or cash flows. Due to the adoption of the standard using the retrospective cumulative-effect adjustment method, the Company recorded $ (6.8) million cumulative-effect adjustment net of taxes to its opening retained earnings. (See Note 7 .) Fair Value Measurement Disclosures Effective January 1, 2020, Sirius Group adopted ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement , which modifies the disclosure requirements of fair value measurements. The adoption of this guidance did not have any impact on the consolidated financial statements but expanded disclosure of the ranges and weighted averages of significant unobservable inputs used in Level 3 fair values. (See Note 9 .) Simplifying the Accounting for Income Taxes Effective January 1, 2020, Sirius Group adopted ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which eliminates certain exceptions, and clarifies and simplifies certain aspects of accounting for income taxes. Sirius Group has fully adopted all provisions of the guidance with consideration of the various transition methods. Sirius Group adopted the removal of the exception to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. The removal of this exception allowed Sirius Group to record a benefit for a year-to-date loss in excess of its forecasted loss in certain jurisdictions. The removal of this exception was applied prospectively to the Income tax benefit (expense) line on the Consolidated Statements of Income. Sirius Group adopted all other provisions in the guidance, including the requirement for an entity to recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax through a cumulative-effect adjustment to retained earnings. These provisions did not have a material impact on the Consolidated Financial Statements or were not applicable to Sirius Group.

Significant transactions

Significant transactions	3 Months Ended
	Mar. 31, 2020
Significant transactions
Significant transactions	Significant transactions Loss portfolio transfer On January 23, 2020, Sirius Group entered into a loss portfolio transfer with Pacific Re, Inc. Under the agreement, Sirius Group received $ 69.7 million in cash and assumed net undiscounted loss and LAE reserves with the same value. In addition, Sirius Group recognized Gross written premium and Loss and losses adjustment expenses for $ 69.7 million.

Segment information

Segment information	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Segment information	Segment information On December 31, 2019, Sirius Group completed an internal reorganization and beginning on January 1, 2020, Sirius Group's reportable segments consist of four reportable segments – Global Reinsurance, Global Accident & Health ("Global A&H"), U.S. Specialty, and Runoff & Other. The accounting policies of the reportable segments are the same as those used for the preparation of the Company's consolidated financial statements. The Company's Global Reinsurance, Global A&H, U.S. Specialty, and Runoff & Other reportable segments each have managers who are responsible for the overall profitability of their respective segments and who are directly accountable to the Company's chief operating decision maker, the Chief Executive Officer ("CEO") of the Company. The CEO assesses segment operating performance, allocates capital, and makes resource allocation decisions based on Technical profit (loss), Underwriting profit (loss), and Underwriting profit (loss), including net service fee revenue. Segment results are shown prior to corporate eliminations. Corporate eliminations are shown to reconcile to consolidated Technical profit (loss), consolidated Underwriting profit (loss) and consolidated Underwriting profit (loss), including net service fee revenue. Sirius Group does not allocate its assets by segment, with the exception of goodwill and intangible assets, and, accordingly, investment income is not allocated to each segment. The internal reorganization had no impact to the allocation of goodwill and intangible assets to the Global A&H segment. Where applicable, all prior periods presented have been revised to conform to this new presentation. Global Reinsurance Global Reinsurance consists of Sirius Group's underwriting lines of business that offer Other Property, Property Catastrophe Excess Reinsurance, Agriculture Reinsurance, Aviation & Space, Marine & Energy, Trade Credit, Contingency, and Casualty Reinsurance: Other Property —Sirius Group participates in the broker market for property reinsurance treaties written on a proportional and excess of loss basis. For Sirius Group's international business, the book consists of treaty, written on both a proportional and excess of loss basis, facultative, and primary business, primarily in Europe, Asia and Latin America. In the United States, the book predominantly centers on significant participations on proportional and excess of loss treaties mostly in the excess and surplus lines segment of the market. Property Catastrophe Excess Reinsurance —Property catastrophe excess of loss reinsurance treaties cover losses from catastrophic events. Sirius Group writes a worldwide book with the largest concentration of exposure in Europe and the United States. The U.S. book written in Bermuda has a national account focus supporting principally the lower and/or middle layers of large capacity programs. Additionally, Stockholm writes a U.S. book mainly consisting of select small regional and standard lines carriers. The exposures written in the international book are diversified across many countries, regions, perils and layers. Agriculture Reinsurance —Sirius Group provides stop-loss reinsurance coverage to companies writing U.S. government-sponsored multi-peril crop insurance ("MPCI"). Sirius Group's participation is net of the government's stop-loss reinsurance protection. Sirius Group also provides coverage for crop-hail and certain named perils when bundled with MPCI business. Sirius Group also writes agriculture business outside of the United States. Aviation & Space —Sirius Group provides aviation insurance that covers loss of or damage to an aircraft and the aircraft operations' liability to passengers, cargo and hull as well as to third parties. Additionally, liability arising out of non-aircraft operations such as hangars, airports and aircraft products can be covered. Space insurance primarily covers loss of or damage to a satellite during launch and in orbit. The book consists of treaty, written on both a proportional and excess of loss basis, facultative, and primary business. Marine & Energy —Sirius Group provides marine & energy reinsurance, primarily written on an excess of loss and proportional basis. Coverage offered includes damage to ships and goods in transit, marine liability lines, and offshore energy industry insurance. Sirius Group also writes yacht business, both on reinsurance and a primary basis. The marine & energy portfolio is diversified across many countries and regions. Trade Credit —Sirius Group writes credit and bond reinsurance worldwide. The bulk of the business is traditional short-term commercial credit insurance, covering pre-agreed domestic and export sales of goods and services with typical coverage periods of 60 to 120 days . Losses under these policies are correlated to adverse changes in a respective country's gross national product. Contingency —Sirius Group underwrote a contingency insurance book primarily for event cancellation and non-appearance. Additionally, coverage for probability based risks with prize redemption was also offered. The contingency insurance business was exited in 2018 with no new exposures written; however, Sirius Group continues to offer this class on a treaty reinsurance basis on a selective basis for a few key clients. Casualty Reinsurance —Sirius Group underwrites a cross section of all casualty lines, including general liability, umbrella, auto, workers compensation, professional liability, and other specialty classes, written on a proportional and excess of loss basis. Global A&H Global A&H consists of Sirius Group’s insurance and reinsurance business, and the managing general underwriting (“MGU”) units (which include ArmadaCorp Capital, LLC ("Armada") and International Medical Group, Inc. ("IMG")). Armada’s products are offered in the United States while IMG and the insurance and reinsurance business write accident and health products on a worldwide basis: Accident and Health insurance and reinsurance —Sirius Group is an insurer of accident and health business in the United States and internationally, on either an admitted or surplus lines basis, as well as a reinsurer of medical expense, travel and personal accident on a treaty or facultative basis worldwide. The MGU unit writes health insurance business worldwide through IMG and within the United States via Armada. U.S. Specialty U.S. Specialty consists of Sirius Group's specialty insurance product offerings, which currently includes Environmental, Surety, and Workers’ Compensation. Environmental underwrites a pure environmental insurance book in the United States consisting of four core products that revolve around pollution coverage, which are premises pollution liability, contractor's pollution liability, contractor's pollution and professional liability. Surety underwrites commercial surety bonds, including non-construction contract bonds, in a broad range of business segments in the United States. Workers’ Compensation , is a state-mandated insurance program that provides medical, disability, survivor, burial, and rehabilitation benefits to employees who are injured or killed due to a work-related injury or illness. Runoff & Other Runoff & Other includes the results of Sirius Global Solutions Holding Company ("Sirius Global Solutions"), which specializes in the acquisition and management of runoff liabilities for insurance and reinsurance companies, both in the United States and internationally, as well as asbestos risks, environmental risks and other long-tailed liability exposures. The following tables summarize the segment results for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, 2020 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Corporate Elimination Total Gross written premiums $ 465.3 $ 262.1 $ 20.8 $ 69.4 $ — $ 817.6 Net written premiums $ 345.4 $ 200.7 $ 15.2 $ 68.6 $ — $ 629.9 Net earned insurance and reinsurance premiums $ 235.0 $ 117.9 $ 12.8 $ 69.0 $ — $ 434.7 Loss and allocated LAE (1) (257.2 ) (80.3 ) (7.7 ) (68.9 ) — (414.1 ) Insurance and reinsurance acquisition expenses (50.9 ) (30.8 ) (3.0 ) (0.4 ) 10.4 (74.7 ) Technical profit (73.1 ) 6.8 2.1 (0.3 ) 10.4 (54.1 ) Unallocated LAE (2) (5.0 ) (1.7 ) (0.1 ) (0.8 ) (5.4 ) (13.0 ) Other underwriting expenses (21.3 ) (5.6 ) (5.2 ) (0.9 ) (5.0 ) (38.0 ) Underwriting income (99.4 ) (0.5 ) (3.2 ) (2.0 ) — (105.1 ) Service fee revenue (3) — 35.9 — — (11.0 ) 24.9 Managing general underwriter unallocated LAE — (6.0 ) — — 6.0 — Managing general underwriter other underwriting expenses — (5.0 ) — — 5.0 — General and administrative expenses, MGU + Runoff & Other (4) — (14.2 ) — (1.5 ) — (15.7 ) Underwriting (loss) income, including net service fee income (99.4 ) 10.2 (3.2 ) (3.5 ) — (95.9 ) Net investment income 13.5 Net realized investment gains 20.3 Net unrealized investment (losses) gains (43.8 ) Net foreign exchange gains 18.5 Other revenue (5) (20.6 ) General and administrative expenses (6) (16.4 ) Intangible asset amortization expenses (3.9 ) Interest expense on debt (7.8 ) Pre-tax (loss) income $ (136.1 ) Underwriting Ratios Loss ratio 111.6 % 69.6 % 60.9 % NM NM 98.3 % Acquisition expense ratio 21.7 % 26.1 % 23.4 % NM NM 17.2 % Other underwriting expense ratio 9.1 % 4.7 % 40.6 % NM NM 8.7 % Combined ratio (7) 142.4 % 100.4 % 124.9 % NM NM 124.2 % Goodwill and intangible assets (8) $ — $ 568.6 $ — $ 8.1 $ — $ 576.7 (1) Loss and allocated loss adjustment expenses ("LAE") are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (2) Unallocated LAE are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (3) Service fee revenue is part of Other revenue on the Consolidated Statements of Income (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (4) General and administrative expenses, MGU + Runoff & Other is part of General and administrative expenses on the Consolidated Statements of Income (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (5) Other revenue is presented net of Service fee revenue and is comprised mainly of losses from derivatives (see Note 12 ) (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (6) General and administrative expenses are presented net of General and administrative expenses, MGU + Runoff & Other (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (7) Ratios considered not meaningful ("NM") to Runoff & Other and Corporate Elimination. (8) Sirius Group does not allocate its assets by segment, with the exception of goodwill and intangible assets. For the three months ended March 31, 2019 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Corporate Elimination Total Gross written premiums $ 435.0 $ 169.3 $ 16.6 $ 1.4 $ — $ 622.3 Net written premiums $ 335.9 $ 134.9 $ 13.6 $ 0.4 $ — $ 484.8 Net earned insurance and reinsurance premiums $ 211.3 $ 96.1 $ 4.1 $ 0.4 $ — $ 311.9 Loss and allocated LAE (1) (107.8 ) (63.2 ) (2.4 ) (1.1 ) — (174.5 ) Insurance and reinsurance acquisition expenses (45.6 ) (26.6 ) (0.7 ) (0.7 ) 10.3 (63.3 ) Technical profit 57.9 6.3 1.0 (1.4 ) 10.3 74.1 Unallocated LAE (2) (4.0 ) (1.5 ) — (0.5 ) (3.4 ) (9.4 ) Other underwriting expenses (21.6 ) (6.1 ) (2.8 ) (2.1 ) (2.7 ) (35.3 ) Underwriting income 32.3 (1.3 ) (1.8 ) (4.0 ) 4.2 29.4 Service fee revenue (3) — 36.3 — — (11.0 ) 25.3 Managing general underwriter unallocated LAE — (4.1 ) — — 4.1 — Managing general underwriter other underwriting expenses — (2.7 ) — — 2.7 — General and administrative expenses, MGU + Runoff & Other (4) — (16.2 ) — (0.8 ) — (17.0 ) Underwriting (loss) income, including net service fee income 32.3 12.0 (1.8 ) (4.8 ) — 37.7 Net investment income 20.1 Net realized investment gains 9.0 Net unrealized investment (losses) gains 74.0 Net foreign exchange gains 5.1 Other revenue (5) (5.7 ) General and administrative expenses (6) (7.4 ) Intangible asset amortization expenses (3.9 ) Interest expense on debt (7.6 ) Pre-tax (loss) income $ 121.3 Underwriting Ratios Loss ratio 52.9 % 67.3 % 58.5 % NM NM 59.0 % Acquisition expense ratio 21.6 % 27.7 % 17.1 % NM NM 20.3 % Other underwriting expense ratio 10.2 % 6.3 % 68.3 % NM NM 11.3 % Combined ratio (7) 84.7 % 101.3 % 143.9 % NM NM 90.6 % Goodwill and intangible assets (8) $ — $ 584.2 $ — $ 8.1 $ — $ 592.3 (1) Loss and allocated LAE are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (2) Unallocated LAE are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (3) Service fee revenue is part of Other revenue on the Consolidated Statements of Income (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (4) General and administrative expenses, MGU + Runoff & Other is part of General and administrative expenses on the Consolidated Statements of Income (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (5) Other revenue is presented net of Service fee revenue and is comprised mainly of losses from derivatives (see Note 12 ) (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (6) General and administrative expenses are presented net of General and administrative expenses, MGU + Runoff & Other (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (7) Ratios considered not meaningful ("NM") to Runoff & Other and Corporate Elimination. (8) Sirius Group does not allocate its assets by segment, with the exception of goodwill and intangible assets. The following tables provide summary information regarding net premiums written by client location and underwriting location by reportable segment for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, 2020 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Total Net written premiums by client location: United States $ 104.3 $ 180.7 $ 15.2 $ 68.1 $ 368.3 Europe 172.8 7.2 — 0.3 180.3 Canada, the Caribbean, Bermuda and Latin America 29.4 6.5 — — 35.9 Asia and Other 38.9 6.3 — 0.2 45.4 Total net written premium by client location for the three months ended March 31, 2020 $ 345.4 $ 200.7 $ 15.2 $ 68.6 $ 629.9 Net written premiums by underwriting location: United States $ 72.6 $ 131.2 $ 15.2 $ 68.0 $ 287.0 Europe 208.2 69.5 — 0.4 278.1 Canada, the Caribbean, Bermuda and Latin America 48.1 — — — 48.1 Asia and Other 16.5 — — 0.2 16.7 Total written premiums by underwriting location for the three months ended March 31, 2020 $ 345.4 $ 200.7 $ 15.2 $ 68.6 $ 629.9 For the three months ended March 31, 2019 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Total Net written premiums by client location: United States $ 116.6 $ 111.1 $ 13.6 $ 0.2 $ 241.5 Europe 149.5 8.0 — 0.1 157.6 Canada, the Caribbean, Bermuda and Latin America 29.0 5.0 — — 34.0 Asia and Other 40.8 10.8 — 0.1 51.7 Total net written premium by client location for the three months ended March 31, 2019 $ 335.9 $ 134.9 $ 13.6 $ 0.4 $ 484.8 Net written premiums by underwriting location: United States $ 75.7 $ 71.0 $ 13.6 $ 0.2 $ 160.5 Europe 207.0 63.6 — 0.1 270.7 Canada, the Caribbean, Bermuda and Latin America 35.9 — — — 35.9 Asia and Other 17.3 0.3 — 0.1 17.7 Total written premiums by underwriting location for the three months ended March 31, 2019 $ 335.9 $ 134.9 $ 13.6 $ 0.4 $ 484.8

Reserves for unpaid losses and

Reserves for unpaid losses and loss adjustment expenses	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Reserves for unpaid losses and loss adjustment expenses	Reserves for unpaid losses and loss adjustment expenses The following table summarizes the loss and LAE reserve activities of Sirius Group for the three months ended March 31, 2020 and 2019 : Three months ended March 31, (Millions) 2020 2019 Gross beginning balance $ 2,331.5 $ 2,016.7 Less beginning reinsurance recoverable on unpaid losses (410.3 ) (350.2 ) Net loss and LAE reserve balance 1,921.2 1,666.5 Losses and LAE incurred relating to: Current year losses 422.9 167.3 Prior years losses 4.2 16.6 Total net incurred losses and LAE 427.1 183.9 Foreign currency translation adjustment to net loss and LAE reserves (21.8 ) (3.4 ) Loss and LAE paid relating to: Current year losses 43.1 36.2 Prior years losses 208.0 183.8 Total loss and LAE payments 251.1 220.0 Net ending balance 2,075.4 1,627.0 Plus ending reinsurance recoverable on unpaid losses 444.2 349.3 Gross ending balance $ 2,519.6 $ 1,976.3 Loss and LAE development - Three Months Ended March 31, 2020 For the three months ended March 31, 2020 , Sirius Group had net unfavorable loss reserve development of $4.2 million . Increases in loss reserve estimates were primarily recorded in Global Reinsurance ($ 9.1 million) primarily from a loss on a Lion Air crash in the Aviation & Space line of business. These increases were partially offset by favorable loss reserve development in Global A&H ($ 4.2 million). Loss and LAE development - Three Months Ended March 31, 2019 For the three months ended March 31, 2019 , Sirius Group had net unfavorable loss reserve development of $ 16.6 million. The most significant increases in loss reserve estimates were recorded in Global Reinsurance ($ 10.3 million) and Global A&H ($ 5.1 million). The unfavorable loss reserve development in Global Reinsurance was primarily attributable to higher than expected reporting from prior year catastrophe events ($ 15.6 million) mainly Hurricanes Irma, Michael, and Florence. In addition, there was unfavorable loss reserve development in Runoff & Other ($ 1.2 million).

Third party reinsurance

Third party reinsurance	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Third party reinsurance	Third party reinsurance In the normal course of business, Sirius Group seeks to protect its businesses from losses due to concentration of risk and losses arising from catastrophic events by reinsuring with third-party reinsurers. Sirius Group remains liable for risks reinsured in the event that the reinsurer does not honor its obligations under reinsurance contracts. At March 31, 2020 , Sirius Group had reinsurance recoverables on paid losses of $85.7 million and reinsurance recoverables of $444.2 million on unpaid losses. At December 31, 2019 , Sirius Group had reinsurance recoverables on paid losses of $73.9 million and reinsurance recoverables of $410.3 million on unpaid losses. Because retrocessional reinsurance contracts do not relieve Sirius Group of its obligation to its insureds, the collectability of balances due from Sirius Group's reinsurers is important to its financial strength. Sirius Group monitors the financial strength and ratings of retrocessionaires on an ongoing basis. Uncollectible amounts historically have not been significant. (See Note 7 .)

Allowance for expected credit l

Allowance for expected credit losses	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
Allowance for expected credit losses	Allowance for expected credit losses Sirius Group is exposed to credit losses primarily through sales of its insurance and reinsurance products and services. The financial assets in scope of the current expected credit losses impairment model primarily include Sirius Group's premium receivables and reinsurance recoverables. Sirius Group pools the premium receivables and reinsurance recoverables by counterparty credit rating and applies a credit default rate that is determined based on the studies published by the rating agencies (e.g., A.M. Best, Standard & Poor's ("S&P")). In circumstances where ratings are unavailable, Sirius Group applies an internally developed default rate based on historical experience, reference data including research publications, and other relevant inputs. To estimate the allowance for expected credit losses, Sirius Group considered the current and expected future economic and market conditions surrounding the COVID-19 pandemic. To the extent the current environment continues beyond our expectations or deteriorates further, we may experience further increases to our allowance for credit losses related to COVID-19. As of March 31, 2020 , Sirius Group's allowance for expected credit losses is as follows: (in millions) Gross Assets in Scope Allowance for Expected Credit Losses Premiums receivable & Funds held by ceding companies $ 1,224.7 $ 10.6 Reinsurance recoverable on unpaid and paid loss 529.9 3.9 MGU Trade receivables (1) 25.6 0.4 Total as of March 31, 2020 $ 1,780.2 $ 14.9 (1) Included as part of Other assets on the Consolidated Balance Sheet Sirius Group monitors counterparty credit ratings and macroeconomic conditions, and considers the most current A.M. Best and S&P credit ratings to determine the allowance each quarter. Of the total gross assets in scope as of March 31, 2020 , approximately 63% were balances with counterparties rated by either A.M. Best or S&P. Of the total rated, 76% were rated A- or better.

Investment securities

Investment securities	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investment securities	Investment securities Sirius Group's invested assets consist of investment securities and other long-term investments held for general investment purposes. The portfolio of investment securities includes fixed maturity investments, short-term investments, equity securities, and other-long term investments which are all classified as trading securities. Realized and unrealized investment gains and losses on trading securities are reported in pre-tax revenues. Net Investment Income Sirius Group's net investment income is comprised primarily of interest income along with associated amortization of premium and accretion of discount on Sirius Group's fixed maturity investments, dividend income from its equity investments, and interest income from its short-term investments. Net investment income for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 10.3 $ 16.8 Short-term investments 3.3 0.4 Equity securities 2.6 2.7 Other long-term investments 0.2 3.9 Total investment income 16.4 23.8 Investment expenses (2.9 ) (3.7 ) Net investment income $ 13.5 $ 20.1 Net Realized and Unrealized Investment Gains (Losses) Net realized and unrealized investment gains (losses) for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Gross realized gains $ 42.0 $ 14.1 Gross realized (losses) (21.7 ) (5.1 ) Net realized gains on investments (1) 20.3 9.0 Net unrealized gains (losses) on investments (2) (43.8 ) 74.0 Net realized and unrealized gains (losses) on investments $ (23.5 ) $ 83.0 (1) Includes $11.1 and $10.9 of realized gains due to foreign currency for the three months ended March 31, 2020 and 2019 , respectively. (2) Includes $52.7 and $25.0 of unrealized gains due to foreign currency for the three months ended March 31, 2020 and 2019 , respectively. Net realized investment gains Net realized investment gains for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 7.8 $ 6.8 Equity securities 0.5 (0.6 ) Short-term investments 2.8 0.1 Derivative instruments 8.3 (0.6 ) Other long-term investments 0.9 3.3 Net realized investment gains $ 20.3 $ 9.0 Net unrealized investment gains (losses) Net unrealized investment gains (losses) for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 7.9 $ 29.7 Equity securities (69.1 ) 25.1 Short-term investments 15.7 2.7 Derivative instruments 0.1 (0.6 ) Other long-term investments 1.6 17.1 Net unrealized investment gains (losses) $ (43.8 ) $ 74.0 The following table summarizes the amount of total gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 0.3 $ — Equity securities — — Other long-term investments (0.9 ) 8.8 Total unrealized investment (losses) gains – Level 3 investments $ (0.6 ) $ 8.8 Investment Holdings Fixed maturity investments The cost or amortized cost, gross unrealized investment gains (losses), net foreign currency gains (losses), and fair value of Sirius Group's fixed maturity investments as of March 31, 2020 and December 31, 2019 , were as follows: March 31, 2020 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized (losses) Net foreign currency gains (losses) Fair value Corporate debt securities $ 424.5 $ 2.8 $ (5.0 ) $ 22.0 $ 444.3 Asset-backed securities 551.9 1.9 (30.1 ) 0.7 524.4 Residential mortgage-backed securities 443.5 23.1 (1.2 ) 6.5 471.9 U.S. government and government agency 119.9 6.8 (0.1 ) 1.6 128.2 Commercial mortgage-backed securities 97.4 1.6 (5.0 ) 0.3 94.3 Non-U.S. government and government agency 60.4 0.4 (0.4 ) 0.4 60.8 Preferred stocks 5.8 0.9 (0.2 ) — 6.5 U.S. States, municipalities and political subdivision 1.6 — — 0.1 1.7 Total fixed maturity investments $ 1,705.0 $ 37.5 $ (42.0 ) $ 31.6 $ 1,732.1 December 31, 2019 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized (losses) Net foreign currency gains (losses) Fair value Corporate debt securities $ 458.6 $ 5.2 $ (1.2 ) $ 11.5 $ 474.1 Asset-backed securities 489.4 1.4 (3.9 ) (0.1 ) 486.8 Residential mortgage-backed securities 426.2 10.5 (1.4 ) 3.6 438.9 U.S. government and government agency 111.5 0.7 (0.4 ) (1.3 ) 110.5 Commercial mortgage-backed securities 88.5 0.9 (0.6 ) 0.2 89.0 Non-U.S. government and government agency 63.7 — (0.7 ) — 63.0 Preferred stocks 17.0 — — — 17.0 U.S. States, municipalities and political subdivision 1.7 — — — 1.7 Total fixed maturity investments $ 1,656.6 $ 18.7 $ (8.2 ) $ 13.9 $ 1,681.0 The weighted average duration of Sirius Group's fixed income portfolio as of March 31, 2020 was approximately 1.5 years , including short-term investments, and approximately 2.3 years excluding short-term investments. The cost or amortized cost and fair value of Sirius Group's fixed maturity investments as of March 31, 2020 and December 31, 2019 are presented below by contractual maturity. Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties. March 31, 2020 December 31, 2019 (Millions) Cost or amortized cost Fair value Cost or amortized cost Fair value Due in one year or less $ 106.2 $ 112.9 $ 85.0 $ 88.4 Due after one year through five years 429.1 446.3 479.1 490.3 Due after five years through ten years 45.9 47.0 46.3 46.0 Due after ten years 25.2 28.8 25.1 24.6 Mortgage-backed and asset-backed securities 1,092.8 1,090.6 1,004.1 1,014.7 Preferred stocks 5.8 6.5 17.0 17.0 Total $ 1,705.0 $ 1,732.1 $ 1,656.6 $ 1,681.0 The following table summarizes the ratings and fair value of fixed maturity investments held in Sirius Group's investment portfolio as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 AAA $ 588.4 $ 559.8 AA 786.8 724.3 A 208.5 219.0 BBB 88.0 95.8 Other 60.4 82.1 Total fixed maturity investments (1) $ 1,732.1 $ 1,681.0 (1) Credit ratings are assigned based on the following hierarchy: 1) Standard & Poor's ("S&P") and 2) Moody's Investors Service ("Moody's"). At March 31, 2020 , the above totals included $37.8 million of sub-prime securities. Of this total, $ 18.3 million was rated AAA, $ 17.2 million rated AA, $ 2.2 million rated A and $ 0.1 million classified as Other. At December 31, 2019 , the above totals included $43.3 million of sub-prime securities. Of this total, $21.7 million was rated AAA, $18.4 million rated AA, $3.1 million rated A and $0.1 million classified as Other. Equity securities and Other long-term investments The cost or amortized cost, gross unrealized investment gains and losses, net foreign currency gains, and fair values of Sirius Group's equity securities and other long-term investments as of March 31, 2020 and December 31, 2019 , were as follows: March 31, 2020 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized losses Net foreign currency gains Fair value Equity securities $ 409.5 $ 37.4 $ (98.4 ) $ 18.1 $ 366.6 Other long-term investments $ 323.2 $ 50.3 $ (31.7 ) $ 13.7 $ 355.5 December 31, 2019 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized losses Net foreign currency gains Fair value Equity securities $ 379.2 $ 55.6 $ (37.3 ) $ 7.7 $ 405.2 Other long-term investments $ 315.4 $ 49.9 $ (29.3 ) $ 10.8 $ 346.8 Equity securities at fair value consisted of the following as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Fixed income mutual funds $ 192.1 $ 175.3 Common stocks 184.4 228.1 Other equity securities (1) (9.9 ) 1.8 Total Equity securities $ 366.6 $ 405.2 (1) Sirius Group engaged in short selling of certain equity securities for which settlement was pending as of March 31, 2020. Other long-term investments at fair value consisted of the following as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Hedge funds and private equity funds $ 279.6 $ 269.0 Limited liability companies and private equity securities 75.9 77.8 Total other long-term investments $ 355.5 $ 346.8 Hedge Funds and Private Equity Funds Sirius Group holds investments in hedge funds and private equity funds, which are included in other long-term investments. The fair value of these investments has been estimated using the net asset value of the funds. As of March 31, 2020 , Sirius Group held investments in 9 hedge funds and 33 private equity funds. The largest investment in a single fund was $59.4 million as of March 31, 2020 and $51.6 million as of December 31, 2019 . The following table summarizes investments in hedge funds and private equity interests by investment objective and sector as of March 31, 2020 and December 31, 2019 : March 31, 2020 December 31, 2019 (Millions) Fair value Unfunded commitments Fair value Unfunded commitments Hedge funds: Long/short multi-sector $ 49.5 $ — $ 53.0 $ — Distressed mortgage credit 59.4 — 51.6 — Private credit 21.8 — 21.5 — Other 1.1 — 1.4 — Total hedge funds 131.8 — 127.5 — Private equity funds: Energy infrastructure & services 51.5 34.1 53.6 34.6 Multi-sector 16.0 7.8 8.7 7.8 Healthcare 28.2 6.8 25.9 10.4 Life settlement 22.9 — 23.9 — Manufacturing/Industrial 26.3 — 27.6 3.9 Private equity secondaries 0.6 0.8 0.6 0.8 Other 2.3 1.8 1.2 2.6 Total private equity funds 147.8 51.3 141.5 60.1 Total hedge and private equity funds included in Other long-term investments $ 279.6 $ 51.3 $ 269.0 $ 60.1 Redemption of investments in certain hedge funds is subject to restrictions including lock-up periods where no redemptions or withdrawals are allowed, restrictions on redemption frequency, and advance notice periods for redemptions. Amounts requested for redemptions remain subject to market fluctuations until the redemption effective date, which generally falls at the end of the defined redemption period. The following summarizes the March 31, 2020 fair value of hedge funds subject to restrictions on redemption frequency and advance notice period requirements for investments in active hedge funds: Notice Period Redemption Frequency 30-59 days notice 60-89 days notice 90-119 days notice 120+ days notice Total Monthly $ — $ 33.5 $ — $ — $ 33.5 Quarterly 0.6 — — — 0.6 Semi-annual — 0.2 — — 0.2 Annual — 16.0 59.6 21.9 97.5 Total $ 0.6 $ 49.7 $ 59.6 $ 21.9 $ 131.8 Certain of the hedge fund and private equity fund investments in which Sirius Group is invested are no longer active and are in the process of disposing of their underlying investments. Distributions from such funds are remitted to investors as the fund's underlying investments are liquidated. As of March 31, 2020 , no distributions were outstanding from these investments. Investments in private equity funds are generally subject to a "lock-up" period during which investors may not request a redemption. Distributions prior to the expected termination date of the fund may be limited to dividends or proceeds arising from the liquidation of the fund's underlying investments. In addition, certain private equity funds provide an option to extend the lock-up period at either the sole discretion of the fund manager or upon agreement between the fund and the investors. As of March 31, 2020 , investments in private equity funds were subject to lock-up periods as follows: (Millions) 1 - 3 years 3 – 5 years 5 – 10 years Total Private Equity Funds – expected lock up period remaining $ 9.1 $ 2.1 $ 136.6 $ 147.8 Investments Held on Deposit or as Collateral As of March 31, 2020 and December 31, 2019 investments of $971.1 million and $1,309.5 million , respectively, were held in trusts required to be maintained in relation to various reinsurance agreements. Sirius Group's reinsurance operations are required to maintain deposits with certain insurance regulatory agencies in order to maintain their insurance licenses. The fair value of such deposits that are included within total investments totaled $1,002.8 million and $1,315.5 million as of March 31, 2020 and December 31, 2019 , respectively. As of March 31, 2020 , Sirius Group held $0.2 million of collateral in the form of short-term investments associated with Interest Rate Cap agreements. (See Note 12 .) Unsettled investment purchases and sales As of March 31, 2020 and December 31, 2019 Sirius Group reported $53.0 million and $2.3 million , respectively, in Accounts payable on unsettled investment purchases. As of March 31, 2020 and December 31, 2019 , Sirius Group reported $35.2 million and $6.7 million , respectively, in Accounts receivable on unsettled investment sales.

Fair value measurements

Fair value measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements Fair value measurements are categorized into a hierarchy that distinguishes between inputs based on market data from independent sources ("observable inputs") and a reporting entity's internal assumptions based upon the best information available when external market data is limited or unavailable ("unobservable inputs"). Quoted prices in active markets for identical assets or liabilities have the highest priority ("Level 1"), followed by observable inputs other than quoted prices, including prices for similar but not identical assets or liabilities ("Level 2"), and unobservable inputs, including the reporting entity's estimates of the assumptions that market participants would use, having the lowest priority ("Level 3"). The availability of observable inputs can vary from financial instrument to financial instrument and is affected by a wide variety factors including, for example, the type of financial instrument, whether the financial instrument is new and not yet established in the marketplace, and other characteristics particular to the instrument. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires significantly more judgment. Accordingly, the degree of judgment exercised by management in determining fair value is greatest for instruments categorized in Level 3. In periods of market dislocation, the observability of prices and inputs may be reduced for many instruments. This may lead the Company to change the selection of the valuation technique (for example, from market to cash flow approach) or to use multiple valuation techniques to estimate the fair value of a financial instrument. These circumstances could cause an instrument to be reclassified between levels within the fair value hierarchy. Investments valued using Level 1 inputs include fixed maturity investments, primarily investments in U.S. Treasuries Bills and Notes, equity securities, and short-term investments. Investments valued using Level 2 inputs are primarily comprised of fixed maturity investments, which have been disaggregated into classes, including U.S. government and government agency, corporate debt securities, mortgage-backed and asset-backed securities, non-U.S. government and government agency, U.S. state and municipalities and political subdivision and preferred stocks. Investments valued using Level 2 inputs also include certain exchange-traded funds that track U.S. stock indices such as the S&P 500 but are traded on foreign exchanges. Fair value estimates for investments that trade infrequently and have few or no observable market prices are classified as Level 3 measurements. Sirius Group determines when transfers between levels have occurred as of the beginning of the period. Valuation techniques Sirius Group uses outside pricing services to assist in determining fair values for its investments. For investments in active markets, Sirius Group uses the quoted market prices provided by outside pricing services to determine fair value. The outside pricing services Sirius Group uses have indicated that they will only provide prices where observable inputs are available. In circumstances where quoted market prices are unavailable or are not considered reasonable, Sirius Group estimates the fair value using industry standard pricing models and observable inputs such as benchmark yields, reported trades, broker-dealer quotes, issuer spreads, benchmark securities, bids, offers, prepayment speeds, reference data including research publications, and other relevant inputs. Given that many fixed maturity investments do not trade on a daily basis, the outside pricing services evaluate a wide range of fixed maturity investments by regularly drawing parallels from recent trades and quotes of comparable securities with similar features. The characteristics used to identify comparable fixed maturity investments vary by asset type and take into account market convention. The valuation process above is generally applicable to all of Sirius Group's fixed maturity investments. The techniques and inputs specific to asset classes within Sirius Group's fixed maturity investments for Level 2 securities that use observable inputs are as follows: U.S. government and government agency U.S. government and government agency securities consist primarily of debt securities issued by the U.S. Treasury and mortgage pass-through agencies such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and the Government National Mortgage Association. Fixed maturity investments included in U.S. government and government agency securities are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources and integrate other observations from markets and sector news. Evaluations are updated by obtaining broker-dealer quotes and other market information including actual trade volumes, when available. The fair value of each security is individually computed using analytical models that incorporate option-adjusted spreads and other daily interest rate data. Non-U.S. government and government agency Non-U.S. government and government agency securities consist of debt securities issued by non-U.S. governments and their agencies along with supranational organizations (also known as sovereign debt securities). Securities held in these sectors are primarily priced by pricing services that employ proprietary discounted cash flow models to value the securities. Key quantitative inputs for these models are daily observed benchmark curves for treasury, swap, and high issuance credits. The pricing services then apply a credit spread for each security, which is developed by in-depth and real-time market analysis. For securities in which trade volume is low, the pricing services utilize data from more frequently traded securities with similar attributes. These models may also be supplemented by daily market and credit research for international markets. Corporate debt securities Corporate debt securities consist primarily of investment-grade debt of a wide variety of U.S. and non-U.S. corporate issuers and industries. The corporate fixed maturity investments are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources regarding the issuer of the security and obtain credit data, as well as other observations, from markets and sector news. Evaluations are updated by obtaining broker-dealer quotes and other market information including actual trade volumes, when available. The pricing services also consider the specific terms and conditions of the securities, including any specific features that may influence risk. Mortgage-backed and asset-backed securities The fair value of mortgage and asset-backed securities is primarily priced by pricing services using a pricing model that utilizes information from market sources and leveraging similar securities. Key inputs include benchmark yields, reported trades, underlying tranche cash flow data and collateral performance, plus new issue data, as well as broker-dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including issuer, vintage, loan type, collateral attributes, prepayment speeds, default rates, recovery rates, cash flow stress testing, credit quality ratings, and market research publications. U.S. states, municipalities and political subdivisions The U.S. states, municipalities and political subdivisions portfolio contains debt securities issued by U.S. domiciled state and municipal entities. These securities are generally priced by independent pricing services using the techniques described for U.S. government and government agency securities described above. Preferred stocks The fair value of preferred stocks is generally priced by independent pricing services using an evaluated pricing model that calculates the appropriate spread over a comparable security for each issue. Key inputs include exchange prices (underlying and common stock of the same issuer), benchmark yields, reported trades, broker-dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including sector, coupon, credit quality ratings, duration, credit enhancements, early redemption features, and market research publications. Level 3 Investments Level 3 valuations are generated from techniques that use assumptions not observable in the market. These unobservable assumptions reflect Sirius Group's assumptions about what market participants would use in valuing the investment. Generally, certain securities may start out as Level 3 when they are originally issued but, as observable inputs become available in the market, they may be reclassified to Level 2. Sirius Group employs a number of procedures to assess the reasonableness of the fair value measurements for its other long-term investments, including obtaining and reviewing the audited annual financial statements of hedge funds and private equity funds and periodically discussing each fund's pricing with the fund manager. However, since the fund managers do not provide sufficient information to evaluate the pricing inputs and methods for each underlying investment, the inputs are considered to be unobservable. The fair values of Sirius Group's investments in private equity securities and private debt instruments have been classified as Level 3 measurements. They are carried at fair value and are initially valued based on transaction price. Their valuation is subsequently estimated based on available evidence such as a market transaction in similar instruments and other financial information for the issuer. Investments measured using Net Asset Value The fair value of Sirius Group's investments in hedge funds and private equity funds has been determined using net asset value ("NAV"). The hedge fund's administrator provides quarterly updates of fair value in the form of Sirius Group's proportional interest in the underlying fund's NAV, which is deemed to approximate fair value, generally with a three month delay in valuation. The fair value of investment in hedge funds is measured using the NAV practical expedient and therefore has been not categorized within the fair value hierarchy. The private equity funds provide quarterly or semi-annual partnership capital statements with a three or six month delay which are used as a basis for valuation. These private equity investments vary in investment strategies and are not actively traded in any open markets. Due to a lag in reporting, some of the fund managers, fund administrators, or both, are unable to provide final fund valuations as of the Company's reporting date. In these circumstances, Sirius Group estimates the return of the current period and uses all credible information available. This includes utilizing preliminary estimates reported by its fund managers and using other information that is available to Sirius Group with respect to the underlying investments, as necessary. Fair Value Measurements by Level The following tables summarize Sirius Group's financial assets and liabilities measured at fair value as of March 31, 2020 and December 31, 2019 by level: March 31, 2020 (Millions) Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Assets measured at fair value Fixed maturity investments: U.S. Government and government agency $ 128.2 $ 127.1 $ 1.1 $ — Corporate debt securities 444.3 — 444.3 — Residential mortgage-backed securities 471.9 — 471.9 — Asset-backed securities 524.4 — 524.4 — Commercial mortgage-backed securities 94.3 — 94.3 — Non-U.S. government and government agency 60.8 29.7 31.1 — Preferred stocks 6.5 — 3.9 2.6 U.S. States, municipalities, and political subdivision 1.7 — 1.7 — Total fixed maturity investments 1,732.1 156.8 1,572.7 2.6 Equity securities: Fixed income mutual funds 192.1 192.1 — — Common stocks 184.4 184.4 — — Other equity securities (1) (9.9 ) (11.6 ) 1.7 — Total equity securities 366.6 364.9 1.7 — Short-term investments 1,041.8 1,019.5 22.3 — Other long-term investments (2) 75.9 — — 75.9 Total investments $ 3,216.4 $ 1,541.2 $ 1,596.7 $ 78.5 Loan participation 19.9 — — 19.9 Derivative instruments 11.7 1.0 — 10.7 Total assets measured at fair value $ 3,248.0 $ 1,542.2 $ 1,596.7 $ 109.1 Liabilities measured at fair value Contingent consideration liabilities $ 28.3 $ — $ — $ 28.3 Derivative instruments 20.4 0.8 — 19.6 Total liabilities measured at fair value $ 48.7 $ 0.8 $ — $ 47.9 (1) Sirius Group engaged in short selling of certain equity securities for which settlement was pending as of March 31, 2020. (2) Excludes fair value of $279.6 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient. December 31, 2019 (Millions) Fair value Level 1 inputs Level 2 inputs Level 3 inputs Assets measured at fair value Fixed maturity investments: U.S. Government and government agency $ 110.5 $ 109.1 $ 1.4 $ — Corporate debt securities 474.1 — 474.1 — Asset-backed securities 486.8 — 486.8 — Residential mortgage-backed securities 438.9 — 438.9 — Commercial mortgage-backed securities 89.0 — 89.0 — Non-U.S. government and government agency 63.0 31.7 31.3 — Preferred stocks 17.0 — — 17.0 U.S. States, municipalities, and political subdivision 1.7 — 1.7 — Total fixed maturity investments 1,681.0 140.8 1,523.2 17.0 Equity securities: Fixed income mutual funds 175.3 175.3 — — Common stocks 228.1 228.1 — — Other equity securities 1.8 — 1.8 — Total equity securities 405.2 403.4 1.8 — Short-term investments 1,085.2 1,073.7 11.5 — Other long-term investments (1) 77.8 — — 77.8 Total investments $ 3,249.2 $ 1,617.9 $ 1,536.5 $ 94.8 Loan participation 20.0 — — 20.0 Derivative instruments 11.4 1.3 — 10.1 Total assets measured at fair value $ 3,280.6 $ 1,619.2 $ 1,536.5 $ 124.9 Liabilities measured at fair value Contingent consideration liabilities $ 28.2 $ — $ — $ 28.2 Derivative instruments 9.5 0.2 — 9.3 Total liabilities measured at fair value $ 37.7 $ 0.2 $ — $ 37.5 (1) Excludes fair value of $269.0 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient. Rollforward of Level 3 fair value measurements The following tables present changes in Level 3 for financial instruments measured at fair value for the three months ended March 31, 2020 and March 31, 2019 : For the three months ended March 31, 2020 (Millions) Fixed Maturities Other long-term investments (1) Loan Participation Derivative instruments assets & (liabilities) Contingent consideration (liabilities) Balance as of January 1, 2020 $ 17.0 $ 77.8 $ 20.0 $ 0.8 $ (28.2 ) Total realized and unrealized gains (losses) 2.6 (0.9 ) — (13.3 ) (0.1 ) Foreign currency gains (losses) through Other Comprehensive Income — (1.0 ) — — — Purchases — — — — — Sales/Settlements (17.0 ) — (0.1 ) 3.6 — Balance as of March 31, 2020 $ 2.6 $ 75.9 $ 19.9 $ (8.9 ) $ (28.3 ) (1) Excludes fair value of $279.6 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient. For the three months ended March 31, 2019 (Millions) Fixed Maturities Other long-term investments (1) Loan Participation Derivative instruments assets & (liabilities) Contingent consideration (liabilities) Balance as of January 1, 2019 $ 5.4 $ 63.6 $ — $ (0.5 ) $ (28.8 ) Total realized and unrealized gains (losses) — 9.3 — (5.1 ) — Foreign currency gains (losses) through Other Comprehensive Income — (0.7 ) — — — Purchases — 15.8 — — — Sales/Settlements (5.4 ) — — 0.8 — Balance as of March 31, 2019 $ — $ 88.0 $ — $ (4.8 ) $ (28.8 ) (1) Excludes fair value of $301.7 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient. Fair value measurements – transfers between levels There were no transfers between Level 3 and Level 2 measurements during the three months ended March 31, 2020 and 2019 . Significant Unobservable Inputs The table below presents information about the significant unobservable inputs used for recurring fair value measurements for certain Level 3 instruments as of March 31, 2020 and December 31, 2019 , and includes only those instruments for which information about the inputs is reasonably available to Sirius Group, such as data from independent third-party valuation service providers and from internal valuation models. (Millions, except share prices) March 31, 2020 Description Valuation Technique(s) Fair value Unobservable input Private equity securities (1) Share price of recent transaction $ 32.5 Purchase share price 40.6 Loan participation (1) Purchase price of recent transaction $ 19.9 Comparable yields Range - 4.46% - 7.25% Preferred stock (1) Share price of recent transaction $ 17.5 Purchase price 7.74 Private equity securities (1) Multiple of GAAP book value $ 13.3 Book value multiple Range - 0.73x-0.91x Private debt instrument (1) Discounted cash flow $ 6.2 Discount yield Range - 11.87% - 12.32% Private equity securities (1) Purchase price of recent transaction $ 5.1 Purchase price 7.74 Currency swaps (2) Third party appraisal $ 2.4 Broker quote $ 2.4 Preferred stock (1) Purchase price of recent transaction $ 1.9 Purchase price $ 1.9 Currency forwards (2) Third party appraisal $ 1.7 Broker quote $ 1.7 Private equity securities (1) Purchase price of recent transaction $ 1.0 Purchase price $ 10.0 Equity warrants (2) Option pricing model $ 0.9 Strike price $ 0.2 Preferred stock (1) Purchase price of recent transaction $ 0.7 Purchase price $ 0.70 Private equity securities (1) Purchase price of recent transaction $ 0.3 Purchase price $ 0.3 Weather derivatives (2) Third party appraisal $ (13.9 ) Broker quote $ (13.9 ) Contingent consideration External valuation model $ (28.3 ) Discounted future payments $ (28.3 ) (1) As of March 31, 2020 , each asset type consists of one security. (2) See Note 12 for discussion of derivative instruments. (Millions, except share prices) December 31, 2019 Description Valuation Technique(s) Fair value Unobservable input Private equity securities (1) Share price of recent transaction $ 32.5 Purchase share price $ 40.6 Loan participation (1) Purchase price of recent transaction $ 20.0 Purchase price 20.0 Preferred stock (1) Share price of recent transaction $ 17.5 Purchase price $ 7.74 Private equity securities (1) Multiple of GAAP book value $ 14.2 Book value multiple 0.9 Preferred stock (1) Purchase price of recent transaction $ 12.2 Purchase price $ 12.2 Private debt instrument (1) Purchase price of recent transaction $ 7.2 Purchase price $ 9.0 Weather derivatives (2) Third party appraisal $ 7.0 Broker quote $ 7.0 Private equity security (1) Purchase price of recent transaction $ 5.1 Purchase price $ 7.74 Preferred stock (1) Purchase price of recent transaction $ 4.8 Purchase price $ 4.80 Currency forwards (2) Third party appraisal $ 2.7 Broker quote $ 2.7 Private equity securities (1) Purchase price of recent transaction $ 1.0 Purchase price $ 10.0 Equity warrants (2) Option pricing model $ 0.4 Strike price $ 0.2 Private equity securities (1) Purchase price of recent transaction $ 0.3 Purchase price $ 0.3 Currency swaps (2) Third party appraisal $ (3.6 ) Broker quote $ (3.6 ) Currency forwards (2) Third party appraisal $ (5.7 ) Broker quote $ (5.7 ) Contingent consideration External valuation model $ (28.2 ) Discounted future payments $ (28.2 ) (1) As of December 31, 2019 , each asset type consists of one security. (2) See Note 12 for discussion of derivative instruments. Financial instruments disclosed, but not carried at fair value Sirius Group uses various financial instruments in the normal course of its business. The carrying values of Cash, Accrued investment income, certain other assets, Accounts payable on unsettled investment purchases, certain other liabilities, and other financial instruments not included in the table below approximated their fair values at March 31, 2020 and December 31, 2019 , due to their respective short maturities. As these financial instruments are not actively traded, their respective fair values are classified within Level 3. The following table includes financial instruments for which the carrying value differs from the estimated fair values at March 31, 2020 and December 31, 2019 : March 31, 2020 December 31, 2019 (Millions) Fair Value (1) Carrying Value Fair Value (1) Carrying Value Liabilities, Mezzanine equity, and Non-controlling interest: 2017 SEK Subordinated Notes $ 268.3 $ 270.6 $ 294.5 $ 291.2 2016 SIG Senior Notes $ 394.9 $ 394.2 $ 394.5 $ 394.0 Series B preference shares $ 171.4 $ 205.0 $ 186.4 $ 223.0 (1) Fair value estimated by internal pricing and considered a Level 3 measurement.

Debt and standby letters of cre

Debt and standby letters of credit facilities	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Debt and standby letters of credit facilities	Debt and standby letters of credit facilities Sirius Group's debt outstanding as of March 31, 2020 and December 31, 2019 consisted of the following: (Millions) March 31, 2020 Effective Rate (1) December 31, 2019 Effective Rate (1) 2017 SEK Subordinated Notes, at face value $ 274.2 4.2 % $ 295.0 4.0 % Unamortized issuance costs (3.6 ) (3.8 ) 2017 SEK Subordinated Notes, carrying value 270.6 291.2 2016 SIG Senior Notes, at face value 400.0 4.7 % 400.0 4.7 % Unamortized discount (2.2 ) (2.3 ) Unamortized issuance costs (3.6 ) (3.7 ) 2016 SIG Senior Notes, carrying value 394.2 394.0 Total debt $ 664.8 $ 685.2 (1) Effective rate considers the effect of the debt issuance costs. 2017 SEK Subordinated Notes On September 22, 2017, Sirius Group issued floating rate callable subordinated notes denominated in Swedish kronor ("SEK") in the amount of SEK 2,750.0 million (or $346.1 million on date of issuance) at a 100% issue price ("2017 SEK Subordinated Notes"). The 2017 SEK Subordinated Notes were issued in an offering that was exempt from the registration requirements of the Securities Act of 1933 (the "Securities Act"). The 2017 SEK Subordinated Notes bear interest on their principal amount at a floating rate equal to the applicable Stockholm Interbank Offered Rate ("STIBOR") for the relevant interest period plus an applicable margin, payable quarterly in arrears on March 22, June 22, September 22, and December 22 in each year commencing on December 22, 2017, until maturity in September 2047. Beginning on September 22, 2022, the 2017 SEK Subordinated Notes may be redeemed, in whole or in part, at Sirius Group's option. In addition, within 90 days following the occurrence of a Specified Event (as defined below), the 2017 SEK Subordinated Notes may be redeemed, in whole but not in part, at Sirius Group's option. "Specified Event" means (a) an "Additional Amounts Event" in connection with a change in laws, rules or regulations as a result of which Sirius Group is obligated to pay additional amounts on the notes in respect of any withholding or deduction for taxes, (b) a "Tax Event" in connection with a change in laws, rules or regulations as a result of which interest on the notes is no longer fully deductible by Sirius Group for income tax purposes in the applicable jurisdiction (to the extent that such interest was so deductible as of the time of such Tax Event), (c) a "Rating Methodology Event" in connection with a change in, or clarification to, the rating methodology of Standard & Poor's or Fitch that results in a materially unfavorable capital treatment of the notes, or (d) a "Regulatory Event" in connection with a change in, or clarification to, applicable supervisory regulations that results in the notes no longer qualifying as Tier 2 Capital. Sirius Group incurred $4.6 million in expenses related to the issuance of the 2017 SEK Subordinated Notes (including SEK 27.5 million , or $3.5 million , in underwriting fees), which have been deferred and are being recognized into interest expense over the life of the 2017 SEK Subordinated Notes. For the three months ended March 31, 2020 and 2019 , Sirius Group recognized $20.6 million and $11.0 million , respectively, of foreign currency exchange gains on the remeasurement of the 2017 SEK Subordinated Notes into USD from SEK. Taking into effect the amortization of all underwriting and issuance expenses, and applicable STIBOR, the 2017 SEK Subordinated Notes yielded an effective rate of approximately 4.2% and 3.7% annualized for the three months ended March 31, 2020 and 2019 , respectively. Sirius Group recorded $3.0 million and $2.8 million of interest expense, inclusive of amortization of issuance costs on the 2017 SEK Subordinated Notes for the three months ended March 31, 2020 and 2019 , respectively. 2016 SIG Senior Notes On November 1, 2016, Sirius Group issued $400.0 million face value of senior unsecured notes ("2016 SIG Senior Notes") at an issue price of 99.209% for net proceeds of $392.4 million after taking into effect both deferrable and non-deferrable issuance costs. The 2016 SIG Senior Notes were issued in an offering that was exempt from the registration requirements of the Securities Act. The 2016 SIG Senior Notes bear an annual interest rate of 4.6% , payable semi-annually in arrears on May 1, and November 1, in each year commencing on May 1, 2017, until maturity in November 2026. Sirius Group incurred $5.1 million in expenses related to the issuance of the 2016 SIG Senior Notes (including $3.4 million in underwriting fees), which have been deferred and are being recognized into interest expense over the life of the 2016 SIG Senior Notes. Taking into effect the amortization of the original issue discount and all underwriting and issuance expenses, the 2016 SIG Senior Notes yield an effective rate of approximately 4.7% per annum. Sirius Group recorded $4.8 million , inclusive of amortization of issuance costs on the 2016 SIG Senior Notes, for both three month periods ended March 31, 2020 and 2019 . Standby Letter of Credit Facilities On November 9, 2019, Sirius International Insurance Corporation ("Sirius International"), a wholly owned subsidiary of the Company, renewed two standby letter of credit facility agreements totaling $125 million to provide capital support for Lloyd's Syndicate 1945. The first letter of credit is a renewal of a $90 million facility with Nordea Bank Finland Abp, London Branch, which is issued on an unsecured basis. The second letter of credit is a $35 million facility with DNB Bank ASA, Sweden Branch, $25 million of which is issued on an unsecured basis. Each facility is renewable annually. The above referenced facilities are subject to various affirmative, negative and financial covenants that the Company considers to be customary for such borrowings, including certain minimum net worth and maximum debt to capitalization standards. Sirius International has other secured letter of credit and trust arrangements with various financial institutions to support its insurance operations. As of March 31, 2020 and December 31, 2019 , these secured letter of credit and trust arrangements were collateralized by pledged assets and assets in trust of SEK 3.4 billion and SEK 3.4 billion, respectively, or $335.6 million and $363.3 million , respectively (based on the March 31, 2020 and December 31, 2019 SEK to USD exchange rates). As of March 31, 2020 and December 31, 2019 , Sirius America Insurance Company's trust arrangements were collateralized by pledged assets and assets in trust of $47.8 million and $57.7 million , respectively. As of March 31, 2020 and December 31, 2019 , Sirius Bermuda's trust arrangements were collateralized by pledged assets and assets in trust of $513.8 million and $784.0 million , respectively. Revolving Credit Facility In February 2018, Sirius Group, through its indirectly wholly-owned subsidiary Sirius International Group, Ltd. entered into a three -year, $300 million senior unsecured revolving credit facility (the "Facility"). The Facility provides access to loans for working capital and general corporate purposes, and letters of credit to support obligations under insurance and reinsurance agreements and retrocessional agreements. The Facility is subject to various affirmative, negative and financial covenants that Sirius Group considers to be customary for such borrowings, including certain minimum net worth, maximum debt to capitalization, financial strength rating standards, and change in control provisions. As of March 31, 2020 , there were no outstanding borrowings under the Facility. Debt and Standby Letter of Credit Facility Covenants As of March 31, 2020 , Sirius Group was in compliance with all of the covenants under the 2017 SEK Subordinated Notes, the 2016 SIG Senior Notes, the Nordea Bank Finland Abp, London Branch facility, and the DNB Bank ASA, Sweden Branch facility. In addition, as of March 31, 2020 , Sirius Group was in compliance with all of the covenants under the Facility. Interest Total interest expense incurred by Sirius Group for its indebtedness for the three months ended March 31, 2020 and 2019 was $7.8 million and $7.6 million , respectively. Total interest paid by Sirius Group for its indebtedness for the three months ended March 31, 2020 and 2019 was $2.8 million and $2.7 million , respectively.

Income taxes

Income taxes	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income taxes	Income taxes The Company and its Bermuda-domiciled subsidiaries are not subject to Bermuda income tax under current Bermuda law. In the event there is a change in the current law such that taxes are imposed, the Company and its Bermuda-domiciled subsidiaries would be exempt from such tax until March 31, 2035, pursuant to the Bermuda Exempted Undertakings Tax Protection Act of 1966. The Company has subsidiaries and branches that operate in various other jurisdictions around the world that are subject to tax in the jurisdictions in which they operate. The jurisdictions in which the Company's subsidiaries and branches are subject to tax are Australia, Belgium, Canada, Denmark, Germany, Gibraltar, Hong Kong (China), Ireland, Luxembourg, Malaysia, Shanghai (China), Singapore, Spain, Sweden, Switzerland, the United Kingdom, and the United States. Sirius Group reported an income tax expense (benefit) of $(14.8) million and $17.2 million during the three months ended March 31, 2020 and 2019 , respectively, on pre-tax income (loss) of $(136.1) million and $121.3 million , respectively. The effective tax rate for the three months ended March 31, 2020 was 10.9% , which was lower than the Swedish statutory rate of 21.4% (the rate at which the majority of Sirius Group's worldwide operations are taxed) primarily because of valuation allowance recorded against certain deferred tax assets and jurisdictions with pretax losses for which no tax benefit can be recognized. The effective tax rate for the three months ended March 31, 2019 was 14.2% , which was lower than the Swedish statutory rate of 21.4% (the rate at which the majority of Sirius Group's worldwide operations are taxed) primarily because of income recognized in jurisdictions with lower rates than Sweden. In arriving at the effective tax rate for the three months ended March 31, 2020 and 2019 , Sirius Group forecasted all income and expense items including the change in unrealized investment gains (losses) and realized investment gains (losses) for the years ending December 31, 2020 and 2019 . The Tax Cuts and Jobs Act ("TCJA") includes a new Base Erosion and Anti-Abuse Minimum Tax ("BEAT") provision, which is essentially a minimum tax that is potentially applicable to certain otherwise deductible payments made by U.S. entities to non-U.S. affiliates, including cross-border interest payments and reinsurance premiums. The statutory BEAT rate is 10% in 2019-2025, and then rises to 12.5% in 2026 and thereafter. The TCJA also includes provisions for Global Intangible Low-Taxed Income ("GILTI") under which taxes on foreign income are imposed on the excess of a deemed return on tangible assets of certain foreign subsidiaries. Consistent with accounting guidance, Sirius Group will treat BEAT as an in period tax charge when incurred in future periods for which no deferred taxes need to be provided and has made an accounting policy election to treat GILTI taxes in a similar manner. No provision for income taxes related to BEAT or GILTI was recorded as of March 31, 2020 and December 31, 2019 . Sirius Group has capital and liquidity in many of its subsidiaries, some of which may reflect undistributed earnings. If such capital or liquidity were to be paid or distributed to the Company or Sirius Group's subsidiaries, as dividends or otherwise, they may be subject to income or withholding taxes. Sirius Group generally intends to operate, and manage its capital and liquidity, in a tax-efficient manner. However, the applicable tax laws in relevant countries are still evolving, including in response to guidance from the Organisation for Economic Cooperation and Development. Accordingly, such payments or earnings may be subject to income or withholding tax in jurisdictions where they are not currently taxed or at higher rates of tax than currently taxed, and the applicable tax authorities could attempt to apply income or withholding tax to past earnings or payments. In April 2020, the European Court of Justice (the “ECJ”) published a decision disallowing the eligibility of an unrelated Gibraltar company for a European Union directive providing relief from withholding taxes on cross-border dividends. More generally, as a result of Brexit, it is projected that Gibraltar companies will cease to be eligible for European Union tax directives from January 1, 2021. The Company has a subsidiary organized in Gibraltar which has been a party to cross-border transactions with affiliates. Accordingly, the Company is currently evaluating the potential tax consequences of both the ECJ decision and Brexit to legacy and future transactions involving this Gibraltar subsidiary, and is assessing whether these developments could materially impact the Company’s provision for income taxes. Deferred tax asset, net of valuation allowance Sirius Group's net deferred tax liability, net of the valuation allowance as of March 31, 2020 is $12.5 million . Of the $12.5 million , $27.0 million relates to net deferred tax assets in U.S. subsidiaries, $133.0 million relates to net deferred tax assets in Luxembourg subsidiaries, $182.7 million relates to net deferred tax liabilities in Sweden subsidiaries, and $10.2 million relates to other net deferred tax asset. Sirius Group records a valuation allowance against deferred tax assets if it becomes more likely than not that all or a portion of a deferred tax asset will not be realized. Changes in valuation allowances from period to period are included in income tax expense in the period of change. In determining whether or not a valuation allowance, or change therein, is warranted, Sirius Group considers factors such as prior earnings history, expected future earnings, carryback and carryforward periods and strategies that if executed would result in the realization of a deferred tax asset. It is possible that certain planning strategies or projected earnings in certain subsidiaries may not be feasible to utilize the entire deferred tax asset, which could result in material changes to Sirius Group's deferred tax assets and tax expense. Uncertain tax positions Recognition of the benefit of a given tax position is based upon whether a company determines that it is more likely than not that a tax position will be sustained upon examination based upon the technical merits of the position. In evaluating the more likely than not recognition threshold, Sirius Group must presume that the tax position will be subject to examination by a taxing authority with full knowledge of all relevant information. If the recognition threshold is met, then the tax position is measured at the largest amount of benefit that is more than 50% likely of being realized upon ultimate settlement. As of March 31, 2020 , the total reserve for unrecognized tax benefits is $42.8 million . If Sirius Group determines in the future that its reserves for unrecognized tax benefits on permanent differences and interest and penalties are not needed, the reversal of $42.6 million of such reserves as of March 31, 2020 would be recorded as an income tax benefit and would impact the effective tax rate. If Sirius Group determines in the future that its reserves for unrecognized tax benefits on temporary differences are not needed, the reversal of $0.2 million of such reserves as of March 31, 2020 would not impact the effective tax rate due to deferred tax accounting but would accelerate the payment of cash to the taxing authority. Most of Sirius Group's reserves for unrecognized tax benefits on permanent differences relate to interest deductions denied by the Swedish Tax Authority ("STA"), as described further below. The STA has denied deductions claimed by two of the Company's Swedish subsidiaries in certain tax years for interest paid on intra-group debt instruments. Sirius Group has challenged the STA's denial in court based on the technical merits. In October 2018, one of the Swedish subsidiaries received an adverse decision from Sweden's Administrative Court, which Sirius Group has appealed. Sirius Group has taken into account this and other relevant developments in applicable Swedish tax law and has established a reserve for this uncertain tax position. As of March 31, 2020 , the total amount of such reserve was $42.0 million . In connection with this matter, Sirius Group has also taken into account the Stock Purchase Agreement ("SPA") by which Sirius Group was sold to CMIG International Holding Pte. Ltd ("CMIG International") in 2016 and has recorded an indemnification asset. Pursuant to the SPA, the seller agreed to indemnify the buyer and Sirius Group for, among other things, (1) any additional tax liability in excess of Sirius Group's accounting for uncertain tax positions for tax periods prior to the sale of Sirius Group to CMIG International, and (2) an impairment in Sirius Group's net deferred tax assets resulting from a final determination by a tax authority. While Sirius Group intends to continue challenging the STA's denial based on the technical merits (including appealing the adverse court decision received in October 2018), the ultimate resolution of these tax disputes is uncertain and no assurance can be given that there will be no material changes to Sirius Group's operating results or balance sheet in connection with these uncertain tax positions or the related indemnification. With few exceptions, Sirius Group is no longer subject to U.S. federal, state or non-U.S. income tax examinations by tax authorities for years before 2015.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives Interest Rate Cap Sirius Group entered into an interest rate swap ("Interest Rate Cap") with two financial institutions where it paid an upfront premium and in return receives a series of quarterly payments based on the 3-month London Interbank Offered Rate at the time of payment. The Interest Rate Cap does not qualify for hedge accounting. Changes in fair value are recognized as unrealized gains or losses and are presented within Other revenue. The fair value of the interest rate cap has been estimated using a single broker quote and, accordingly, has been classified as a Level 3 measurement as of March 31, 2020 and December 31, 2019 . Collateral held is recorded within short-term investments with an equal amount recognized as a liability to return collateral. Sirius Group's liability to return that collateral is based on the amounts provided by the counterparties and investment earnings thereon. As at March 31, 2020 and December 31, 2019 , Sirius Group held collateral balances of $0.2 million at the end of each period. Foreign Currency Risk Derivatives Sirius Group executes foreign currency forwards, swaps, and futures to manage foreign currency exposure. The foreign currency risk derivatives are not designated or accounted for under hedge accounting. Changes in fair value are recognized as unrealized gains or losses and are presented within Net foreign exchange gains. The fair value of the swaps and forwards are estimated using a single broker quote and accordingly, classified as a Level 3 measurement. The fair value of the futures is widely available and have quoted prices in active markets and accordingly, were classified as a Level 1 measurement. Sirius Group did not provide or hold any collateral associated with the foreign currency risk derivatives. Weather Derivatives Sirius Group holds assets and assumes liabilities related to weather and weather contingent risk management products. Weather and weather contingent derivative contracts are entered into with the objective of generating profits in normal climatic conditions. Accordingly, Sirius Group's weather and weather contingent derivatives are not designed to meet the criteria for hedge accounting under GAAP. Sirius Group receives payment of premium at the contract inception in exchange for bearing the risk of variations in a quantifiable weather index. Changes in fair value are recognized as unrealized gains or losses and are presented within Other revenue. The fair value of the weather derivatives was estimated using a broker quote. Because of the significance of the unobservable inputs used to estimate the fair value of Sirius Group's weather risk contracts, the fair value measurements of the contracts are deemed to be Level 3 measurements in the fair value hierarchy as of March 31, 2020 and December 31, 2019 . Sirius Group does not provide or hold any collateral associated with the weather derivatives. Equity Contracts Sirius Group executes trades in equity futures contracts, call options, and put options to hedge against positions in Common equities. The equity contracts are not designated or accounted for under hedge accounting. Changes in fair value are presented within Net unrealized investment (losses) gains . The fair value of the equity contracts is widely available and have quoted prices in active markets and accordingly, were classified as a Level 1 measurement. Equity Warrants Sirius Group holds restricted equity warrants as part of its investment strategy. The equity warrants are not designated or accounted for under hedge accounting. Changes in fair value are presented within Net unrealized investment (losses) gains . The fair value of the equity warrants is estimated using a single broker quote and accordingly, classified as a Level 3 measurement. Sirius Group did not provide or hold any collateral associated with the equity warrants. The following tables summarize information on the classification and amount of the fair value of derivatives not designated as hedging instruments within the Company's Consolidated Balance Sheets as at March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Derivatives not designated as hedging instruments Notional Value Asset derivative at fair value (1) Liability derivative at fair value (2) Notional Value Asset derivative at fair value (1) Liability derivative at fair value (2) Interest rate cap $ 250.0 $ — $ — $ 250.0 $ — $ — Foreign currency swaps $ 90.0 $ 2.4 $ — $ 90.0 $ — $ 3.6 Foreign currency forwards $ 215.2 $ 7.3 $ 5.7 $ (30.0 ) $ 2.7 $ 5.7 Weather derivatives $ 105.9 $ — $ 13.9 $ 110.7 $ 7.0 $ — Equity futures contracts $ 20.1 $ — $ — $ 34.5 $ — $ — Equity call options $ 1.9 $ 0.1 $ — $ — $ — $ — Equity put options $ 11.4 $ 1.0 $ 0.8 $ 31.0 $ 1.3 $ 0.2 Equity warrants $ 0.9 $ 0.9 $ — $ 0.4 $ 0.4 $ — (1) Asset derivatives are classified within Other assets within the Company's Consolidated Balance Sheets at March 31, 2020 and December 31, 2019 . (2) Liability derivatives are classified within Other liabilities within the Company's Consolidated Balance Sheets at March 31, 2020 and December 31, 2019 . The following table summarizes information on the classification and net impact on earnings, recognized in the Company's Consolidated Statements of Income relating to derivatives during the three months ended March 31, 2020 and 2019 : (Millions) For the three months ended March 31, Derivatives not designated as hedging instruments Classification of gains (losses) recognized in earnings 2020 2019 Interest rate cap Other revenues $ — $ (0.1 ) Foreign currency swaps Net foreign exchange gains $ 6.0 $ 0.8 Foreign currency forwards Net foreign exchange gains $ 0.5 $ 0.2 Weather derivatives Other revenues $ (20.4 ) $ (6.0 ) Equity futures contracts Net realized investment gains (losses) $ 2.9 $ (0.6 ) Equity futures contracts Net unrealized investment gains $ (1.0 ) $ (0.2 ) Equity put options Net realized investment gains (losses) $ 5.5 $ — Equity put options Net unrealized investment gains $ 0.5 $ (0.4 ) Equity warrants Net unrealized investment gains $ 0.5 $ —

Share-based compensation

Share-based compensation	3 Months Ended
	Mar. 31, 2020
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation	Share-based compensation Sirius Group's compensation plans include grants for various types of share-based and non-share-based compensation awards to key employees and directors of Sirius Group. As of March 31, 2020 , Sirius Group's share-based compensation awards consist of performance shares units ("PSUs"), restricted share units ("RSUs"), restricted stock and options. Sirius Group recognized $ 1.2 million and $0.2 million of compensation expense under the share-based awards during the three months ended March 31, 2020 and 2019 , respectively. Sirius Group paid $ 0.3 million and $ 3.3 million to employees for share-based awards during the three months ended March 31, 2020 and 2019 , respectively. The following tables present unrecognized compensation cost associated with unvested awards and weighted average period over which it is expected to be recognized: (Millions) March 31, 2020 PSUs - IPO Incentive Awards PSUs - 2019 Long Term Incentive (LTI) RSUs Stock Options 2018 Long Term Incentive Plan (LTIP) Unrecognized compensation cost related to unvested awards $ 2.6 $ 1.1 $ 9.8 $ 1.8 $ 0.2 Weighted average recognition period (years) 1.8 years 1.8 years 1.7 years 1.9 years 0.8 years As of March 31, 2019 , there were $ 34.3 million of unrecognized share-based compensation costs, which are expected to be recognized over two to three years . The following table summarizes outstanding share-settled awards as of March 31, 2020 : As of and for the quarter ended March 31, 2020 Number of Shares PSUs - IPO Incentive Awards PSUs - 2019 LTI RSUs Stock Options 2018 Long Term Incentive Plan (LTIP) Unvested, beginning of period 555,163 391,136 1,353,852 1,374,945 870,471 Granted — — — — — Vested — — — — — Forfeited 11,967 8,809 33,015 — 14,372 Unvested, end of period 543,196 382,327 1,320,837 1,374,945 856,099 For the three months ended March 31, 2019, Sirius Group granted employees 401,311 PSUs, 1,411,714 RSUs, and 1,374,945 stock options. Cash-Settled Awards From time to time, the Company may issue cash-settled awards to its employees. In February 2020, Sirius Group awarded long-term incentive compensation to certain employees of the Company in the form of three -year, cliff-vested, phantom performance shares and phantom restricted shares that are payable in cash. Phantom performance shares compound through the end of the three-year award period based on the performance metrics during the period. The performance goals were determined by the Compensation Committee of the Board of Directors upon granting of awards. During the three months ended March 31, 2020 , the Company recognized an expense of $ 1.6 million related to this award. In addition, Sirius Group issued retention awards to certain key employees of the Company that vest and are paid in equal proportions on or prior to March 15, 2020 and on or prior to March 15, 2021, subject to continued employment on the applicable vesting date. In total the retention awards issued under this retention program were $13.8 million, of which, $6.9 million was paid on March 15, 2020. During the three months ended March 31, 2020 , the Company recognized an expense of $6.3 million in General and administrative expenses.

Common shareholder's equity, me

Common shareholder's equity, mezzanine equity, and non-controlling interests	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Common shareholder's equity, mezzanine equity, and non-controlling interests	Common shareholder's equity, mezzanine equity, and non-controlling interests Common shareholder's equity The authorized share capital of the Company consists of 500,000,000 Common shares, $0.01 par value per share, and 100,000,000 Preference shares, $0.01 par value per share. The following table presents changes in the Company's issued and outstanding Common shares as of March 31, 2020 and 2019 , respectively: Three months ended March 31, (Millions) 2020 2019 Common shares: Shares issued and outstanding, beginning of period 115,299,341 115,151,251 Issuance of shares to directors and employees — 111,052 Shares issued and outstanding, end of period 115,299,341 115,262,303 Dividends The Company did not pay dividends to common shareholders during the three months ended March 31, 2020 and 2019 . Mezzanine equity Series B Preference Shares Sirius Group has issued 11,901,670 of the 15,000,000 designated Series B preference shares, with a par value of $0.01 per share. The Series B preference shares rank senior to common shares with respect to dividend rights, rights of liquidation, winding-up, or dissolution of the Company and junior to all of the Company's existing and future policyholder obligations and debt obligations. Without the consent of the holders of the Series B preference shares, the Company may not issue any class or series of shares that rank senior or pari passu with the Series B preference shares as to the payment of dividends or as to distribution of assets upon any voluntary or involuntary liquidation, winding-up or dissolution of the Company, if the aggregate gross proceeds from the issuance of all such senior or pari passu shares equals or exceeds $100 million . The Company adjusts the carrying value of the Series B preference shares to equal the redemption value at the end of each reporting period. At March 31, 2020 and December 31, 2019 , the balance of the Series B preference shares was $ 199.6 million and $223.0 million , respectively. Non-controlling interests Non-controlling interests consist of the ownership interests of non-controlling shareholders in consolidated entities and are presented separately on the balance sheet. At March 31, 2020 and December 31, 2019 , Sirius Group's balance sheet included $2.6 million and $2.4 million , respectively, in non-controlling interests. The following tables show the change in non-controlling interest for the three months ended March 31, 2020 and 2019 : (Millions) For the three months ended March 31, 2020 For the three months ended March 31, 2019 Non-controlling interests, beginning of the period $ 2.4 $ 1.7 Net income attributable to non-controlling interests 0.2 0.4 Other, net — 0.1 Non-controlling interests, end of the period $ 2.6 $ 2.2 Alstead Re As of March 31, 2020 and December 31, 2019 , Sirius Group recorded non-controlling interest of $ 2.5 million and $ 2.3 million, respectively, in Alstead Re Insurance Company ("Alstead Re"). (See Note 17 .)

Earnings per share

Earnings per share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Earnings per share	Earnings per share Basic earnings per share is computed by dividing net income available to Sirius Group common shareholders by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income (loss) available to Sirius Group common shareholders on a diluted basis by the weighted-average number of common shares outstanding adjusted to give effect to potentially dilutive securities. The Series B preference shares qualify as participating securities, which requires the application of the two-class method to compute both basic and diluted earnings per share. The two-class method is an earnings allocation formula that treats participating securities as having rights to earnings that would otherwise have been available to common shareholders. The Series B preference shares have no obligation to absorb losses of the Company in periods of net loss. The following table sets forth the computation of basic and diluted earnings per common share for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, (Millions, except share and per share information) 2020 2019 Basic earnings per share Numerator: Net income $ (121.3 ) $ 104.1 Less: Income attributable to non-controlling interests (0.2 ) (0.4 ) Less: Change in carrying value of Series B preference shares 23.4 (8.4 ) Net income available for dividends out of undistributed earnings $ (98.1 ) $ 95.3 Less: Earnings attributable to Series B preference shares — (8.9 ) Net income available to Sirius Group common shareholders $ (98.1 ) $ 86.4 Denominator: Weighted average shares outstanding for basic earnings per share 115,262,302 115,182,331 Basic earnings per share $ (0.85 ) $ 0.75 Diluted earnings per share Numerator: Net income available to Sirius Group common shareholders $ (98.1 ) $ 86.4 Add: Change in carrying value of Series B preference shares (23.4 ) 8.4 Net income available to Sirius Group common shareholders on a diluted basis $ (121.5 ) $ 94.8 Denominator: Weighted average shares outstanding for basic earnings per share 115,262,302 115,182,331 Add: Series B preference shares 11,901,670 11,901,670 Add: Unvested performance share units and restricted share units — 251,313 Weighted average shares outstanding for diluted earnings per share (1) 127,163,972 127,335,314 Diluted earnings per share $ (0.96 ) $ 0.74 (1) For the three months ended March 31, 2020 , there were a total of 15,972,398 potentially dilutive securities excluded from the calculation of Diluted earnings per share. For the three months ended March 31, 2019 , there were 19,510,830 potentially dilutive securities excluded from the calculation of Diluted earnings per share.

Investments in unconsolidated e

Investments in unconsolidated entities	3 Months Ended
	Mar. 31, 2020
Investments in unconsolidated entities
Investments in unconsolidated entities	Investments in unconsolidated entities Sirius Group's investments in unconsolidated entities are included within Other long-term investments and consist of investments in common equity securities or similar instruments, which give Sirius Group the ability to exert significant influence over the investee's operating and financial policies ("equity method eligible unconsolidated entities"). Such investments may be accounted for under either the equity method or, alternatively, Sirius Group may elect to account for them under the fair value option. The following table presents the components of Other long-term investments as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Equity method eligible unconsolidated entities, at fair value $ 151.8 $ 151.9 Other unconsolidated investments, at fair value (1) 203.7 194.9 Total Other long-term investments (2) $ 355.5 $ 346.8 (1) Includes Other long-term investments that are not equity method eligible. (2) There were no investments accounted for using the equity method as of March 31, 2020 and December 31, 2019 . Equity method eligible unconsolidated entities, at fair value Sirius Group has elected the fair value option to account for its equity method eligible investments accounted for as part of Other long-term investments for consistency of presentation with the rest of its investment portfolio. The following table presents Sirius Group's investments in equity method eligible unconsolidated entities as of March 31, 2020 and December 31, 2019 : Ownership interest as of Investee March 31, 2020 December 31, 2019 Instrument Held BE Reinsurance Limited 24.9 % 24.9 % Common shares BioVentures Investors (Offshore) IV LP 73.0 % 73.0 % Units Camden Partners Strategic Fund V (Cayman), LP 39.4 % 39.4 % Units Diamond LS I LP 16.0 % 16.0 % Units Gateway Fund LP 19.3 % 15.0 % Units Monarch 12.8 % 12.8 % Units New Energy Capital Infrastructure Credit Fund LP 30.5 % 30.5 % Units New Energy Capital Infrastructure Offshore Credit Fund LP 30.5 % 30.5 % Units Pie Preferred Stock (1) 30.1 % 30.1 % Preferred shares Pie Series B Preferred Stock (1) 22.4 % 22.4 % Preferred shares Quintana Energy Partners 21.8 % 21.8 % Units Tuckerman Capital V LP 48.3 % 48.3 % Units Tuckerman Capital V Co-Investment I LP 48.3 % 48.1 % Units (1) Sirius Group holds investments in several financing instruments of Pie Insurance Holding, Inc.

Variable interest entities

Variable interest entities	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable interest entities	Variable interest entities Sirius Group consolidates the results of operations and financial position of every voting interest entity ("VOE") in which it has a controlling financial interest and VIEs in which it is considered to be the primary beneficiary. The consolidation assessment, including the determination as to whether an entity qualifies as a VOE or VIE, depends on the facts and circumstances surrounding each entity. Sirius Group has determined that Alstead Re is a VIE for which Sirius Group is the primary beneficiary and is required to consolidate it. The following table presents Alstead Re's assets and liabilities, as classified in the Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Assets: Fixed maturity investments $ 3.6 $ 3.9 Short-term investments 0.5 0.5 Cash 0.1 0.1 Total investments 4.2 4.5 Insurance and reinsurance premiums receivable (0.5 ) (0.3 ) Funds held by ceding companies 3.4 3.4 Deferred acquisition costs 0.1 0.3 Other assets — — Total assets $ 7.2 $ 7.9 Liabilities Loss and loss adjustment expense reserves $ 0.4 $ 0.5 Unearned insurance and reinsurance premiums 0.1 0.6 Other liabilities 0.1 0.1 Total liabilities $ 0.6 $ 1.2 Sirius Group is a passive investor in certain third-party-managed hedge and private equity funds, some of which are VIEs. Sirius Group is not involved in the design or establishment of these VIEs, nor does it actively participate in the management of the VIEs. The exposure to loss from these investments is limited to the carrying value of the investments at the balance sheet date. Sirius Group calculates maximum exposure to loss to be (i) the amount invested in the debt or equity of the VIE, (ii) the notional amount of VIE assets or liabilities where Sirius Group has also provided credit protection to the VIE with the VIE as the referenced obligation, and (iii) other commitments and guarantees to the VIE. Sirius Group does not have any VIEs that it sponsors nor any VIEs where it has recourse to it or has provided a guarantee to the VIE interest holders. The following table presents total assets of unconsolidated VIEs in which Sirius Group holds a variable interest, as well as the maximum exposure to loss associated with these VIEs: Maximum Exposure to Loss (Millions) Total VIE Assets On-Balance Sheet Off-Balance Sheet Total March 31, 2020 Other long-term investments (1) $ 250.7 $ 103.0 $ 8.8 $ 111.8 Total at March 31, 2020 $ 250.7 $ 103.0 $ 8.8 $ 111.8 December 31, 2019 Other long-term investments (1) $ 257.8 $ 102.6 $ 16.3 $ 118.9 Total at December 31, 2019 $ 257.8 $ 102.6 $ 16.3 $ 118.9 (1) Comprised primarily of hedge funds and private equity funds.

Transactions with related parti

Transactions with related parties	3 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
Transactions with related parties	Transactions with related parties (Re)insurance contracts In the normal course of business, Sirius Group enters into insurance and reinsurance contracts with certain of its insurance and MGU affiliates, or their subsidiaries. During the three months ended March 31, 2020 and 2019 , these contracts resulted in gross written premiums of $41.3 million and $24.1 million, respectively. As of March 31, 2020 and December 31, 2019 , Sirius Group had total receivables due from affiliates of $31.0 million and $16.1 million , respectively. As of both March 31, 2020 and December 31, 2019 , Sirius Group had total payables due to affiliates of $ 0.9 million. Other Meyer "Sandy" Frucher is the Company's Chairman of the Board of Directors and was also Vice Chairman of Nasdaq, Inc. ("Nasdaq") until December 2019. On January 1, 2020, Mr. Frucher concluded his tenure as Vice Chairman of Nasdaq and assumed the role of Strategic Advisor. The Company is traded on the Nasdaq Global Select Market and has business transactions that are related to its listing on the exchange under the normal course of business. (See Note 3 .)

Commitments and contingencies

Commitments and contingencies	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Legal Proceedings Sirius Group, and the insurance and reinsurance industry in general, are routinely subject to claims related litigation and arbitration in the normal course of business, as well as litigation and arbitration that do not arise from, or are directly related to, claims activity. Sirius Group estimates of the costs of settling matters routinely encountered in claims activity are reflected in the reserves for unpaid loss and LAE. (See Note 5 .) Sirius Group considers the requirements of ASC 450, Contingencies ("ASC 450"), when evaluating its exposure to non-claims related litigation and arbitration. ASC 450 requires that accruals be established for litigation and arbitration if it is probable that a loss has been incurred and it can be reasonably estimated. ASC 450 also requires that litigation and arbitration be disclosed if it is probable that a loss has been incurred or it there is a reasonable possibility that a loss may have been incurred. Management has considered all pending and/or threatened non-claims related litigation and has not identified any matters triggering disclosure under ASC 450. Leases Sirius Group leases office space and equipment under various noncancelable operating lease agreements. The average life of the office leases is 7 years and the equipment leases is 3 years . During the three months ended March 31, 2020 and March 31, 2019 , Sirius Group recognized operating lease expense of $3.0 million and $2.6 million, respectively, including property taxes and routine maintenance expense as well as rental expenses related to short term leases. As of March 31, 2020 and December 31, 2019 , Sirius Group had $26.1 million and $27.4 million of operating lease right-of-use assets, respectively, included in Other assets. As of March 31, 2020 and December 31, 2019 , Sirius Group had $27.8 million and $29.3 million of operating lease liability, respectively, included in Other liabilities. The following table presents the lease balances within the Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019 : (millions) Balance Sheet Classification March 31, 2020 December 31, 2019 Operating lease right-of-use assets Other assets $26.1 $27.4 Current lease liabilities Other liabilities $7.6 $8.3 Non-current lease liabilities Other liabilities $20.2 $21.0 The following table presents weighted average remaining lease term and weighted average discount rate as of March 31, 2020 : Weighted average lease term (years) as at March 31, 2020 Leased offices 7 years Leased equipment 3 years Weighted average discount rate: Leased offices 3.6 % Leased equipment 3.4 % The following table presents future annual minimum rental payments required under non-cancellable leases and the present value discount to arrive at total lease liability as of March 31, 2020 : (Millions) Future Payments 2020 $ 6.5 2021 8.1 2022 7.2 2023 4.7 2024 2.3 2025 and after 1.1 Total future annual minimum rental payments as of March 31, 2020 29.9 Less: present value discount (2.1 ) Total lease liability as of March 31, 2020 $ 27.8 As of March 31, 2020 , the Company's future operating lease obligations that have not yet commenced are immaterial.

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The accompanying Unaudited Consolidated Financial Statements at March 31, 2020 , have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") and the rules and regulations of the U.S. Securities and Exchange Commission ("SEC") for interim financial information. The accompanying Unaudited Consolidated Financial Statements present the consolidated results of operations, financial condition, and cash flows of the Company and its subsidiaries and those entities in which the Company has control and a majority economic interest as well as those variable interest entities ("VIEs") that meet the requirements for consolidation. All significant intercompany transactions have been eliminated in consolidation. These Unaudited Consolidated Financial Statements do not include all disclosures normally included in annual financial statements prepared in accordance with GAAP and should be read in conjunction with the Audited Consolidated Financial Statements and the related notes for the year ended December 31, 2019 . The consolidated financial information as of December 31, 2019 included herein has been derived from the Audited Consolidated Financial Statements as of December 31, 2019 . Effective January 1, 2020, the Company changed its reportable segments. The change in reportable segments had no impact on the Company’s historical consolidated financial positions, results of operations or cash flows as previously reported. Where applicable, all prior periods presented have been revised to conform to this new presentation. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. In the opinion of management, the accompanying Unaudited Consolidated Financial Statements reflect all adjustments (consisting of normally recurring accruals) necessary for a fair statement of results on an interim basis. Tabular dollar amounts are in millions, with the exception of share and per share amounts. All amounts are reported in U.S. dollars, except where noted otherwise.
Recently adopted changes in accounting principles and accounting pronouncements	Recently adopted changes in accounting principles Credit losses Effective January 1, 2020, Sirius Group adopted Accounting Standards Update ("ASU") 2016-13, Measurement of Credit Losses on Financial Instruments (ASC 326), which establishes new guidance for the recognition of credit losses for financial assets measured at amortized cost ("current expected credit losses" or "CECL"). The guidance applies to financial assets that have the contractual right to receive cash, including reinsurance receivables and recoverables and requires reporting entities to estimate the credit losses expected over the life of a credit exposure using historical information, current information and reasonable and supportable forecasts that affect the collectability of the financial asset. The expected credit losses, and subsequent adjustments to such losses, are recorded through an allowance account that is deducted from the amortized cost basis of the financial asset, with the net carrying value of the financial asset presented on the consolidated balance sheet at the amount expected to be collected. Sirius Group adopted the new guidance using a modified retrospective transition method through a cumulative-effect adjustment to retained earnings. As a result of the adoption of the new guidance, Sirius Group estimated a total CECL allowance of $ 14.9 million. The adoption of this guidance did not materially impact our results of operations or cash flows. Due to the adoption of the standard using the retrospective cumulative-effect adjustment method, the Company recorded $ (6.8) million cumulative-effect adjustment net of taxes to its opening retained earnings. (See Note 7 .) Fair Value Measurement Disclosures Effective January 1, 2020, Sirius Group adopted ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement , which modifies the disclosure requirements of fair value measurements. The adoption of this guidance did not have any impact on the consolidated financial statements but expanded disclosure of the ranges and weighted averages of significant unobservable inputs used in Level 3 fair values. (See Note 9 .) Simplifying the Accounting for Income Taxes Effective January 1, 2020, Sirius Group adopted ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which eliminates certain exceptions, and clarifies and simplifies certain aspects of accounting for income taxes. Sirius Group has fully adopted all provisions of the guidance with consideration of the various transition methods. Sirius Group adopted the removal of the exception to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. The removal of this exception allowed Sirius Group to record a benefit for a year-to-date loss in excess of its forecasted loss in certain jurisdictions. The removal of this exception was applied prospectively to the Income tax benefit (expense) line on the Consolidated Statements of Income. Sirius Group adopted all other provisions in the guidance, including the requirement for an entity to recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax through a cumulative-effect adjustment to retained earnings. These provisions did not have a material impact on the Consolidated Financial Statements or were not applicable to Sirius Group.

Segment information (Tables)

Segment information (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Summary of segment results	The following tables summarize the segment results for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, 2020 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Corporate Elimination Total Gross written premiums $ 465.3 $ 262.1 $ 20.8 $ 69.4 $ — $ 817.6 Net written premiums $ 345.4 $ 200.7 $ 15.2 $ 68.6 $ — $ 629.9 Net earned insurance and reinsurance premiums $ 235.0 $ 117.9 $ 12.8 $ 69.0 $ — $ 434.7 Loss and allocated LAE (1) (257.2 ) (80.3 ) (7.7 ) (68.9 ) — (414.1 ) Insurance and reinsurance acquisition expenses (50.9 ) (30.8 ) (3.0 ) (0.4 ) 10.4 (74.7 ) Technical profit (73.1 ) 6.8 2.1 (0.3 ) 10.4 (54.1 ) Unallocated LAE (2) (5.0 ) (1.7 ) (0.1 ) (0.8 ) (5.4 ) (13.0 ) Other underwriting expenses (21.3 ) (5.6 ) (5.2 ) (0.9 ) (5.0 ) (38.0 ) Underwriting income (99.4 ) (0.5 ) (3.2 ) (2.0 ) — (105.1 ) Service fee revenue (3) — 35.9 — — (11.0 ) 24.9 Managing general underwriter unallocated LAE — (6.0 ) — — 6.0 — Managing general underwriter other underwriting expenses — (5.0 ) — — 5.0 — General and administrative expenses, MGU + Runoff & Other (4) — (14.2 ) — (1.5 ) — (15.7 ) Underwriting (loss) income, including net service fee income (99.4 ) 10.2 (3.2 ) (3.5 ) — (95.9 ) Net investment income 13.5 Net realized investment gains 20.3 Net unrealized investment (losses) gains (43.8 ) Net foreign exchange gains 18.5 Other revenue (5) (20.6 ) General and administrative expenses (6) (16.4 ) Intangible asset amortization expenses (3.9 ) Interest expense on debt (7.8 ) Pre-tax (loss) income $ (136.1 ) Underwriting Ratios Loss ratio 111.6 % 69.6 % 60.9 % NM NM 98.3 % Acquisition expense ratio 21.7 % 26.1 % 23.4 % NM NM 17.2 % Other underwriting expense ratio 9.1 % 4.7 % 40.6 % NM NM 8.7 % Combined ratio (7) 142.4 % 100.4 % 124.9 % NM NM 124.2 % Goodwill and intangible assets (8) $ — $ 568.6 $ — $ 8.1 $ — $ 576.7 (1) Loss and allocated loss adjustment expenses ("LAE") are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (2) Unallocated LAE are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (3) Service fee revenue is part of Other revenue on the Consolidated Statements of Income (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (4) General and administrative expenses, MGU + Runoff & Other is part of General and administrative expenses on the Consolidated Statements of Income (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (5) Other revenue is presented net of Service fee revenue and is comprised mainly of losses from derivatives (see Note 12 ) (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (6) General and administrative expenses are presented net of General and administrative expenses, MGU + Runoff & Other (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (7) Ratios considered not meaningful ("NM") to Runoff & Other and Corporate Elimination. (8) Sirius Group does not allocate its assets by segment, with the exception of goodwill and intangible assets. For the three months ended March 31, 2019 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Corporate Elimination Total Gross written premiums $ 435.0 $ 169.3 $ 16.6 $ 1.4 $ — $ 622.3 Net written premiums $ 335.9 $ 134.9 $ 13.6 $ 0.4 $ — $ 484.8 Net earned insurance and reinsurance premiums $ 211.3 $ 96.1 $ 4.1 $ 0.4 $ — $ 311.9 Loss and allocated LAE (1) (107.8 ) (63.2 ) (2.4 ) (1.1 ) — (174.5 ) Insurance and reinsurance acquisition expenses (45.6 ) (26.6 ) (0.7 ) (0.7 ) 10.3 (63.3 ) Technical profit 57.9 6.3 1.0 (1.4 ) 10.3 74.1 Unallocated LAE (2) (4.0 ) (1.5 ) — (0.5 ) (3.4 ) (9.4 ) Other underwriting expenses (21.6 ) (6.1 ) (2.8 ) (2.1 ) (2.7 ) (35.3 ) Underwriting income 32.3 (1.3 ) (1.8 ) (4.0 ) 4.2 29.4 Service fee revenue (3) — 36.3 — — (11.0 ) 25.3 Managing general underwriter unallocated LAE — (4.1 ) — — 4.1 — Managing general underwriter other underwriting expenses — (2.7 ) — — 2.7 — General and administrative expenses, MGU + Runoff & Other (4) — (16.2 ) — (0.8 ) — (17.0 ) Underwriting (loss) income, including net service fee income 32.3 12.0 (1.8 ) (4.8 ) — 37.7 Net investment income 20.1 Net realized investment gains 9.0 Net unrealized investment (losses) gains 74.0 Net foreign exchange gains 5.1 Other revenue (5) (5.7 ) General and administrative expenses (6) (7.4 ) Intangible asset amortization expenses (3.9 ) Interest expense on debt (7.6 ) Pre-tax (loss) income $ 121.3 Underwriting Ratios Loss ratio 52.9 % 67.3 % 58.5 % NM NM 59.0 % Acquisition expense ratio 21.6 % 27.7 % 17.1 % NM NM 20.3 % Other underwriting expense ratio 10.2 % 6.3 % 68.3 % NM NM 11.3 % Combined ratio (7) 84.7 % 101.3 % 143.9 % NM NM 90.6 % Goodwill and intangible assets (8) $ — $ 584.2 $ — $ 8.1 $ — $ 592.3 (1) Loss and allocated LAE are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (2) Unallocated LAE are part of Loss and loss adjustment expenses on the Consolidated Statements of Income (the sum of Loss and allocated LAE and Unallocated LAE is equal to Loss and loss adjustment expenses on the Consolidated Statements of Income). (3) Service fee revenue is part of Other revenue on the Consolidated Statements of Income (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (4) General and administrative expenses, MGU + Runoff & Other is part of General and administrative expenses on the Consolidated Statements of Income (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (5) Other revenue is presented net of Service fee revenue and is comprised mainly of losses from derivatives (see Note 12 ) (the sum of Service fee revenue and Other revenue is equal to Other revenue on the Consolidated Statements of Income). (6) General and administrative expenses are presented net of General and administrative expenses, MGU + Runoff & Other (the sum of General and administrative expenses, MGU + Runoff & Other and General and administrative expenses is equal to General and administrative expenses on the Consolidated Statements of Income). (7) Ratios considered not meaningful ("NM") to Runoff & Other and Corporate Elimination. (8) Sirius Group does not allocate its assets by segment, with the exception of goodwill and intangible assets.
Summary information regarding net premiums written by client location and underwriting location by reportable segment	The following tables provide summary information regarding net premiums written by client location and underwriting location by reportable segment for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, 2020 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Total Net written premiums by client location: United States $ 104.3 $ 180.7 $ 15.2 $ 68.1 $ 368.3 Europe 172.8 7.2 — 0.3 180.3 Canada, the Caribbean, Bermuda and Latin America 29.4 6.5 — — 35.9 Asia and Other 38.9 6.3 — 0.2 45.4 Total net written premium by client location for the three months ended March 31, 2020 $ 345.4 $ 200.7 $ 15.2 $ 68.6 $ 629.9 Net written premiums by underwriting location: United States $ 72.6 $ 131.2 $ 15.2 $ 68.0 $ 287.0 Europe 208.2 69.5 — 0.4 278.1 Canada, the Caribbean, Bermuda and Latin America 48.1 — — — 48.1 Asia and Other 16.5 — — 0.2 16.7 Total written premiums by underwriting location for the three months ended March 31, 2020 $ 345.4 $ 200.7 $ 15.2 $ 68.6 $ 629.9 For the three months ended March 31, 2019 (Expressed in millions of U.S. dollars) Global Reinsurance Global A&H U.S. Specialty Runoff & Other Total Net written premiums by client location: United States $ 116.6 $ 111.1 $ 13.6 $ 0.2 $ 241.5 Europe 149.5 8.0 — 0.1 157.6 Canada, the Caribbean, Bermuda and Latin America 29.0 5.0 — — 34.0 Asia and Other 40.8 10.8 — 0.1 51.7 Total net written premium by client location for the three months ended March 31, 2019 $ 335.9 $ 134.9 $ 13.6 $ 0.4 $ 484.8 Net written premiums by underwriting location: United States $ 75.7 $ 71.0 $ 13.6 $ 0.2 $ 160.5 Europe 207.0 63.6 — 0.1 270.7 Canada, the Caribbean, Bermuda and Latin America 35.9 — — — 35.9 Asia and Other 17.3 0.3 — 0.1 17.7 Total written premiums by underwriting location for the three months ended March 31, 2019 $ 335.9 $ 134.9 $ 13.6 $ 0.4 $ 484.8

Reserves for unpaid losses an_2

Reserves for unpaid losses and loss adjustment expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Summary of the loss and LAE reserve activities	The following table summarizes the loss and LAE reserve activities of Sirius Group for the three months ended March 31, 2020 and 2019 : Three months ended March 31, (Millions) 2020 2019 Gross beginning balance $ 2,331.5 $ 2,016.7 Less beginning reinsurance recoverable on unpaid losses (410.3 ) (350.2 ) Net loss and LAE reserve balance 1,921.2 1,666.5 Losses and LAE incurred relating to: Current year losses 422.9 167.3 Prior years losses 4.2 16.6 Total net incurred losses and LAE 427.1 183.9 Foreign currency translation adjustment to net loss and LAE reserves (21.8 ) (3.4 ) Loss and LAE paid relating to: Current year losses 43.1 36.2 Prior years losses 208.0 183.8 Total loss and LAE payments 251.1 220.0 Net ending balance 2,075.4 1,627.0 Plus ending reinsurance recoverable on unpaid losses 444.2 349.3 Gross ending balance $ 2,519.6 $ 1,976.3

Allowance for expected credit_2

Allowance for expected credit losses (Tables)	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
Summary of allowance for expected credit losses	As of March 31, 2020 , Sirius Group's allowance for expected credit losses is as follows: (in millions) Gross Assets in Scope Allowance for Expected Credit Losses Premiums receivable & Funds held by ceding companies $ 1,224.7 $ 10.6 Reinsurance recoverable on unpaid and paid loss 529.9 3.9 MGU Trade receivables (1) 25.6 0.4 Total as of March 31, 2020 $ 1,780.2 $ 14.9 (1) Included as part of Other assets on the Consolidated Balance Sheet

Investment securities (Tables)

Investment securities (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of net investment income	Net investment income for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 10.3 $ 16.8 Short-term investments 3.3 0.4 Equity securities 2.6 2.7 Other long-term investments 0.2 3.9 Total investment income 16.4 23.8 Investment expenses (2.9 ) (3.7 ) Net investment income $ 13.5 $ 20.1
Schedule of net realized and unrealized investment gains (losses)	Net realized and unrealized investment gains (losses) for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Gross realized gains $ 42.0 $ 14.1 Gross realized (losses) (21.7 ) (5.1 ) Net realized gains on investments (1) 20.3 9.0 Net unrealized gains (losses) on investments (2) (43.8 ) 74.0 Net realized and unrealized gains (losses) on investments $ (23.5 ) $ 83.0 (1) Includes $11.1 and $10.9 of realized gains due to foreign currency for the three months ended March 31, 2020 and 2019 , respectively. (2) Includes $52.7 and $25.0 of unrealized gains due to foreign currency for the three months ended March 31, 2020 and 2019 , respectively.
Schedule of net realized investment gains (losses)	Net realized investment gains for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 7.8 $ 6.8 Equity securities 0.5 (0.6 ) Short-term investments 2.8 0.1 Derivative instruments 8.3 (0.6 ) Other long-term investments 0.9 3.3 Net realized investment gains $ 20.3 $ 9.0
Schedule of net unrealized investment gains (losses)	The following table summarizes the amount of total gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 0.3 $ — Equity securities — — Other long-term investments (0.9 ) 8.8 Total unrealized investment (losses) gains – Level 3 investments $ (0.6 ) $ 8.8 Net unrealized investment gains (losses) for the three months ended March 31, 2020 and 2019 consisted of the following: For the three months ended March 31, (Millions) 2020 2019 Fixed maturity investments $ 7.9 $ 29.7 Equity securities (69.1 ) 25.1 Short-term investments 15.7 2.7 Derivative instruments 0.1 (0.6 ) Other long-term investments 1.6 17.1 Net unrealized investment gains (losses) $ (43.8 ) $ 74.0
Schedule of investment securities and other long-term investments	Equity securities at fair value consisted of the following as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Fixed income mutual funds $ 192.1 $ 175.3 Common stocks 184.4 228.1 Other equity securities (1) (9.9 ) 1.8 Total Equity securities $ 366.6 $ 405.2 (1) Sirius Group engaged in short selling of certain equity securities for which settlement was pending as of March 31, 2020. Other long-term investments at fair value consisted of the following as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Hedge funds and private equity funds $ 279.6 $ 269.0 Limited liability companies and private equity securities 75.9 77.8 Total other long-term investments $ 355.5 $ 346.8 The cost or amortized cost, gross unrealized investment gains (losses), net foreign currency gains (losses), and fair value of Sirius Group's fixed maturity investments as of March 31, 2020 and December 31, 2019 , were as follows: March 31, 2020 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized (losses) Net foreign currency gains (losses) Fair value Corporate debt securities $ 424.5 $ 2.8 $ (5.0 ) $ 22.0 $ 444.3 Asset-backed securities 551.9 1.9 (30.1 ) 0.7 524.4 Residential mortgage-backed securities 443.5 23.1 (1.2 ) 6.5 471.9 U.S. government and government agency 119.9 6.8 (0.1 ) 1.6 128.2 Commercial mortgage-backed securities 97.4 1.6 (5.0 ) 0.3 94.3 Non-U.S. government and government agency 60.4 0.4 (0.4 ) 0.4 60.8 Preferred stocks 5.8 0.9 (0.2 ) — 6.5 U.S. States, municipalities and political subdivision 1.6 — — 0.1 1.7 Total fixed maturity investments $ 1,705.0 $ 37.5 $ (42.0 ) $ 31.6 $ 1,732.1 December 31, 2019 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized (losses) Net foreign currency gains (losses) Fair value Corporate debt securities $ 458.6 $ 5.2 $ (1.2 ) $ 11.5 $ 474.1 Asset-backed securities 489.4 1.4 (3.9 ) (0.1 ) 486.8 Residential mortgage-backed securities 426.2 10.5 (1.4 ) 3.6 438.9 U.S. government and government agency 111.5 0.7 (0.4 ) (1.3 ) 110.5 Commercial mortgage-backed securities 88.5 0.9 (0.6 ) 0.2 89.0 Non-U.S. government and government agency 63.7 — (0.7 ) — 63.0 Preferred stocks 17.0 — — — 17.0 U.S. States, municipalities and political subdivision 1.7 — — — 1.7 Total fixed maturity investments $ 1,656.6 $ 18.7 $ (8.2 ) $ 13.9 $ 1,681.0 The cost or amortized cost, gross unrealized investment gains and losses, net foreign currency gains, and fair values of Sirius Group's equity securities and other long-term investments as of March 31, 2020 and December 31, 2019 , were as follows: March 31, 2020 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized losses Net foreign currency gains Fair value Equity securities $ 409.5 $ 37.4 $ (98.4 ) $ 18.1 $ 366.6 Other long-term investments $ 323.2 $ 50.3 $ (31.7 ) $ 13.7 $ 355.5 December 31, 2019 (Millions) Cost or amortized cost Gross unrealized gains Gross unrealized losses Net foreign currency gains Fair value Equity securities $ 379.2 $ 55.6 $ (37.3 ) $ 7.7 $ 405.2 Other long-term investments $ 315.4 $ 49.9 $ (29.3 ) $ 10.8 $ 346.8
Schedule of fixed maturity investment by contractual maturity	The cost or amortized cost and fair value of Sirius Group's fixed maturity investments as of March 31, 2020 and December 31, 2019 are presented below by contractual maturity. Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties. March 31, 2020 December 31, 2019 (Millions) Cost or amortized cost Fair value Cost or amortized cost Fair value Due in one year or less $ 106.2 $ 112.9 $ 85.0 $ 88.4 Due after one year through five years 429.1 446.3 479.1 490.3 Due after five years through ten years 45.9 47.0 46.3 46.0 Due after ten years 25.2 28.8 25.1 24.6 Mortgage-backed and asset-backed securities 1,092.8 1,090.6 1,004.1 1,014.7 Preferred stocks 5.8 6.5 17.0 17.0 Total $ 1,705.0 $ 1,732.1 $ 1,656.6 $ 1,681.0
Schedule of ratings and fair value of fixed maturity investments	The following table summarizes the ratings and fair value of fixed maturity investments held in Sirius Group's investment portfolio as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 AAA $ 588.4 $ 559.8 AA 786.8 724.3 A 208.5 219.0 BBB 88.0 95.8 Other 60.4 82.1 Total fixed maturity investments (1) $ 1,732.1 $ 1,681.0 (1) Credit ratings are assigned based on the following hierarchy: 1) Standard & Poor's ("S&P") and 2) Moody's Investors Service ("Moody's").
Summary of investment securities by investment objective and sector	The following table summarizes investments in hedge funds and private equity interests by investment objective and sector as of March 31, 2020 and December 31, 2019 : March 31, 2020 December 31, 2019 (Millions) Fair value Unfunded commitments Fair value Unfunded commitments Hedge funds: Long/short multi-sector $ 49.5 $ — $ 53.0 $ — Distressed mortgage credit 59.4 — 51.6 — Private credit 21.8 — 21.5 — Other 1.1 — 1.4 — Total hedge funds 131.8 — 127.5 — Private equity funds: Energy infrastructure & services 51.5 34.1 53.6 34.6 Multi-sector 16.0 7.8 8.7 7.8 Healthcare 28.2 6.8 25.9 10.4 Life settlement 22.9 — 23.9 — Manufacturing/Industrial 26.3 — 27.6 3.9 Private equity secondaries 0.6 0.8 0.6 0.8 Other 2.3 1.8 1.2 2.6 Total private equity funds 147.8 51.3 141.5 60.1 Total hedge and private equity funds included in Other long-term investments $ 279.6 $ 51.3 $ 269.0 $ 60.1
Schedule of redemption frequency and advance notice period requirements for investments	The following summarizes the March 31, 2020 fair value of hedge funds subject to restrictions on redemption frequency and advance notice period requirements for investments in active hedge funds: Notice Period Redemption Frequency 30-59 days notice 60-89 days notice 90-119 days notice 120+ days notice Total Monthly $ — $ 33.5 $ — $ — $ 33.5 Quarterly 0.6 — — — 0.6 Semi-annual — 0.2 — — 0.2 Annual — 16.0 59.6 21.9 97.5 Total $ 0.6 $ 49.7 $ 59.6 $ 21.9 $ 131.8
Schedule of investment securities by lock-up period.	As of March 31, 2020 , investments in private equity funds were subject to lock-up periods as follows: (Millions) 1 - 3 years 3 – 5 years 5 – 10 years Total Private Equity Funds – expected lock up period remaining $ 9.1 $ 2.1 $ 136.6 $ 147.8

Fair value measurements (Tables

Fair value measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of financial assets and liabilities measured at fair value	The following tables summarize Sirius Group's financial assets and liabilities measured at fair value as of March 31, 2020 and December 31, 2019 by level: March 31, 2020 (Millions) Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Assets measured at fair value Fixed maturity investments: U.S. Government and government agency $ 128.2 $ 127.1 $ 1.1 $ — Corporate debt securities 444.3 — 444.3 — Residential mortgage-backed securities 471.9 — 471.9 — Asset-backed securities 524.4 — 524.4 — Commercial mortgage-backed securities 94.3 — 94.3 — Non-U.S. government and government agency 60.8 29.7 31.1 — Preferred stocks 6.5 — 3.9 2.6 U.S. States, municipalities, and political subdivision 1.7 — 1.7 — Total fixed maturity investments 1,732.1 156.8 1,572.7 2.6 Equity securities: Fixed income mutual funds 192.1 192.1 — — Common stocks 184.4 184.4 — — Other equity securities (1) (9.9 ) (11.6 ) 1.7 — Total equity securities 366.6 364.9 1.7 — Short-term investments 1,041.8 1,019.5 22.3 — Other long-term investments (2) 75.9 — — 75.9 Total investments $ 3,216.4 $ 1,541.2 $ 1,596.7 $ 78.5 Loan participation 19.9 — — 19.9 Derivative instruments 11.7 1.0 — 10.7 Total assets measured at fair value $ 3,248.0 $ 1,542.2 $ 1,596.7 $ 109.1 Liabilities measured at fair value Contingent consideration liabilities $ 28.3 $ — $ — $ 28.3 Derivative instruments 20.4 0.8 — 19.6 Total liabilities measured at fair value $ 48.7 $ 0.8 $ — $ 47.9 (1) Sirius Group engaged in short selling of certain equity securities for which settlement was pending as of March 31, 2020. (2) Excludes fair value of $279.6 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient. December 31, 2019 (Millions) Fair value Level 1 inputs Level 2 inputs Level 3 inputs Assets measured at fair value Fixed maturity investments: U.S. Government and government agency $ 110.5 $ 109.1 $ 1.4 $ — Corporate debt securities 474.1 — 474.1 — Asset-backed securities 486.8 — 486.8 — Residential mortgage-backed securities 438.9 — 438.9 — Commercial mortgage-backed securities 89.0 — 89.0 — Non-U.S. government and government agency 63.0 31.7 31.3 — Preferred stocks 17.0 — — 17.0 U.S. States, municipalities, and political subdivision 1.7 — 1.7 — Total fixed maturity investments 1,681.0 140.8 1,523.2 17.0 Equity securities: Fixed income mutual funds 175.3 175.3 — — Common stocks 228.1 228.1 — — Other equity securities 1.8 — 1.8 — Total equity securities 405.2 403.4 1.8 — Short-term investments 1,085.2 1,073.7 11.5 — Other long-term investments (1) 77.8 — — 77.8 Total investments $ 3,249.2 $ 1,617.9 $ 1,536.5 $ 94.8 Loan participation 20.0 — — 20.0 Derivative instruments 11.4 1.3 — 10.1 Total assets measured at fair value $ 3,280.6 $ 1,619.2 $ 1,536.5 $ 124.9 Liabilities measured at fair value Contingent consideration liabilities $ 28.2 $ — $ — $ 28.2 Derivative instruments 9.5 0.2 — 9.3 Total liabilities measured at fair value $ 37.7 $ 0.2 $ — $ 37.5 (1) Excludes fair value of $269.0 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient.
Rollforward of Level 3 fair value measurements	The following tables present changes in Level 3 for financial instruments measured at fair value for the three months ended March 31, 2020 and March 31, 2019 : For the three months ended March 31, 2020 (Millions) Fixed Maturities Other long-term investments (1) Loan Participation Derivative instruments assets & (liabilities) Contingent consideration (liabilities) Balance as of January 1, 2020 $ 17.0 $ 77.8 $ 20.0 $ 0.8 $ (28.2 ) Total realized and unrealized gains (losses) 2.6 (0.9 ) — (13.3 ) (0.1 ) Foreign currency gains (losses) through Other Comprehensive Income — (1.0 ) — — — Purchases — — — — — Sales/Settlements (17.0 ) — (0.1 ) 3.6 — Balance as of March 31, 2020 $ 2.6 $ 75.9 $ 19.9 $ (8.9 ) $ (28.3 ) (1) Excludes fair value of $279.6 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient. For the three months ended March 31, 2019 (Millions) Fixed Maturities Other long-term investments (1) Loan Participation Derivative instruments assets & (liabilities) Contingent consideration (liabilities) Balance as of January 1, 2019 $ 5.4 $ 63.6 $ — $ (0.5 ) $ (28.8 ) Total realized and unrealized gains (losses) — 9.3 — (5.1 ) — Foreign currency gains (losses) through Other Comprehensive Income — (0.7 ) — — — Purchases — 15.8 — — — Sales/Settlements (5.4 ) — — 0.8 — Balance as of March 31, 2019 $ — $ 88.0 $ — $ (4.8 ) $ (28.8 ) (1) Excludes fair value of $301.7 associated with hedge funds and private equity funds which fair value is measured using NAV practical expedient.
Schedule of significant unobservable inputs used for recurring fair value measurements for Level 3 instruments	The table below presents information about the significant unobservable inputs used for recurring fair value measurements for certain Level 3 instruments as of March 31, 2020 and December 31, 2019 , and includes only those instruments for which information about the inputs is reasonably available to Sirius Group, such as data from independent third-party valuation service providers and from internal valuation models. (Millions, except share prices) March 31, 2020 Description Valuation Technique(s) Fair value Unobservable input Private equity securities (1) Share price of recent transaction $ 32.5 Purchase share price 40.6 Loan participation (1) Purchase price of recent transaction $ 19.9 Comparable yields Range - 4.46% - 7.25% Preferred stock (1) Share price of recent transaction $ 17.5 Purchase price 7.74 Private equity securities (1) Multiple of GAAP book value $ 13.3 Book value multiple Range - 0.73x-0.91x Private debt instrument (1) Discounted cash flow $ 6.2 Discount yield Range - 11.87% - 12.32% Private equity securities (1) Purchase price of recent transaction $ 5.1 Purchase price 7.74 Currency swaps (2) Third party appraisal $ 2.4 Broker quote $ 2.4 Preferred stock (1) Purchase price of recent transaction $ 1.9 Purchase price $ 1.9 Currency forwards (2) Third party appraisal $ 1.7 Broker quote $ 1.7 Private equity securities (1) Purchase price of recent transaction $ 1.0 Purchase price $ 10.0 Equity warrants (2) Option pricing model $ 0.9 Strike price $ 0.2 Preferred stock (1) Purchase price of recent transaction $ 0.7 Purchase price $ 0.70 Private equity securities (1) Purchase price of recent transaction $ 0.3 Purchase price $ 0.3 Weather derivatives (2) Third party appraisal $ (13.9 ) Broker quote $ (13.9 ) Contingent consideration External valuation model $ (28.3 ) Discounted future payments $ (28.3 ) (1) As of March 31, 2020 , each asset type consists of one security. (2) See Note 12 for discussion of derivative instruments. (Millions, except share prices) December 31, 2019 Description Valuation Technique(s) Fair value Unobservable input Private equity securities (1) Share price of recent transaction $ 32.5 Purchase share price $ 40.6 Loan participation (1) Purchase price of recent transaction $ 20.0 Purchase price 20.0 Preferred stock (1) Share price of recent transaction $ 17.5 Purchase price $ 7.74 Private equity securities (1) Multiple of GAAP book value $ 14.2 Book value multiple 0.9 Preferred stock (1) Purchase price of recent transaction $ 12.2 Purchase price $ 12.2 Private debt instrument (1) Purchase price of recent transaction $ 7.2 Purchase price $ 9.0 Weather derivatives (2) Third party appraisal $ 7.0 Broker quote $ 7.0 Private equity security (1) Purchase price of recent transaction $ 5.1 Purchase price $ 7.74 Preferred stock (1) Purchase price of recent transaction $ 4.8 Purchase price $ 4.80 Currency forwards (2) Third party appraisal $ 2.7 Broker quote $ 2.7 Private equity securities (1) Purchase price of recent transaction $ 1.0 Purchase price $ 10.0 Equity warrants (2) Option pricing model $ 0.4 Strike price $ 0.2 Private equity securities (1) Purchase price of recent transaction $ 0.3 Purchase price $ 0.3 Currency swaps (2) Third party appraisal $ (3.6 ) Broker quote $ (3.6 ) Currency forwards (2) Third party appraisal $ (5.7 ) Broker quote $ (5.7 ) Contingent consideration External valuation model $ (28.2 ) Discounted future payments $ (28.2 ) (1) As of December 31, 2019 , each asset type consists of one security. (2) See Note 12 for discussion of derivative instruments.
Schedule of financial instruments disclosed, but not carried at fair value	The following table includes financial instruments for which the carrying value differs from the estimated fair values at March 31, 2020 and December 31, 2019 : March 31, 2020 December 31, 2019 (Millions) Fair Value (1) Carrying Value Fair Value (1) Carrying Value Liabilities, Mezzanine equity, and Non-controlling interest: 2017 SEK Subordinated Notes $ 268.3 $ 270.6 $ 294.5 $ 291.2 2016 SIG Senior Notes $ 394.9 $ 394.2 $ 394.5 $ 394.0 Series B preference shares $ 171.4 $ 205.0 $ 186.4 $ 223.0 (1) Fair value estimated by internal pricing and considered a Level 3 measurement.

Debt and standby letters of c_2

Debt and standby letters of credit facilities (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Schedule of debt outstanding	Sirius Group's debt outstanding as of March 31, 2020 and December 31, 2019 consisted of the following: (Millions) March 31, 2020 Effective Rate (1) December 31, 2019 Effective Rate (1) 2017 SEK Subordinated Notes, at face value $ 274.2 4.2 % $ 295.0 4.0 % Unamortized issuance costs (3.6 ) (3.8 ) 2017 SEK Subordinated Notes, carrying value 270.6 291.2 2016 SIG Senior Notes, at face value 400.0 4.7 % 400.0 4.7 % Unamortized discount (2.2 ) (2.3 ) Unamortized issuance costs (3.6 ) (3.7 ) 2016 SIG Senior Notes, carrying value 394.2 394.0 Total debt $ 664.8 $ 685.2 (1) Effective rate considers the effect of the debt issuance costs.

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of classification and amount of fair value of derivatives not designated as hedging instruments within Consolidated Balance Sheets	The following tables summarize information on the classification and amount of the fair value of derivatives not designated as hedging instruments within the Company's Consolidated Balance Sheets as at March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Derivatives not designated as hedging instruments Notional Value Asset derivative at fair value (1) Liability derivative at fair value (2) Notional Value Asset derivative at fair value (1) Liability derivative at fair value (2) Interest rate cap $ 250.0 $ — $ — $ 250.0 $ — $ — Foreign currency swaps $ 90.0 $ 2.4 $ — $ 90.0 $ — $ 3.6 Foreign currency forwards $ 215.2 $ 7.3 $ 5.7 $ (30.0 ) $ 2.7 $ 5.7 Weather derivatives $ 105.9 $ — $ 13.9 $ 110.7 $ 7.0 $ — Equity futures contracts $ 20.1 $ — $ — $ 34.5 $ — $ — Equity call options $ 1.9 $ 0.1 $ — $ — $ — $ — Equity put options $ 11.4 $ 1.0 $ 0.8 $ 31.0 $ 1.3 $ 0.2 Equity warrants $ 0.9 $ 0.9 $ — $ 0.4 $ 0.4 $ — (1) Asset derivatives are classified within Other assets within the Company's Consolidated Balance Sheets at March 31, 2020 and December 31, 2019 . (2) Liability derivatives are classified within Other liabilities within the Company's Consolidated Balance Sheets at March 31, 2020 and December 31, 2019 .
Schedule of classification and net impact on earnings, recognized in Consolidated Statements of Income relating to derivatives	The following table summarizes information on the classification and net impact on earnings, recognized in the Company's Consolidated Statements of Income relating to derivatives during the three months ended March 31, 2020 and 2019 : (Millions) For the three months ended March 31, Derivatives not designated as hedging instruments Classification of gains (losses) recognized in earnings 2020 2019 Interest rate cap Other revenues $ — $ (0.1 ) Foreign currency swaps Net foreign exchange gains $ 6.0 $ 0.8 Foreign currency forwards Net foreign exchange gains $ 0.5 $ 0.2 Weather derivatives Other revenues $ (20.4 ) $ (6.0 ) Equity futures contracts Net realized investment gains (losses) $ 2.9 $ (0.6 ) Equity futures contracts Net unrealized investment gains $ (1.0 ) $ (0.2 ) Equity put options Net realized investment gains (losses) $ 5.5 $ — Equity put options Net unrealized investment gains $ 0.5 $ (0.4 ) Equity warrants Net unrealized investment gains $ 0.5 $ —

Share-based compensation (Table

Share-based compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Unrecognized Compensation Cost Associated with Unvested Awards and Weighted Average Period Over Which it is Expected to be Recognized	The following tables present unrecognized compensation cost associated with unvested awards and weighted average period over which it is expected to be recognized: (Millions) March 31, 2020 PSUs - IPO Incentive Awards PSUs - 2019 Long Term Incentive (LTI) RSUs Stock Options 2018 Long Term Incentive Plan (LTIP) Unrecognized compensation cost related to unvested awards $ 2.6 $ 1.1 $ 9.8 $ 1.8 $ 0.2 Weighted average recognition period (years) 1.8 years 1.8 years 1.7 years 1.9 years 0.8 years
Summary of Outstanding Share-settled Awards	The following table summarizes outstanding share-settled awards as of March 31, 2020 : As of and for the quarter ended March 31, 2020 Number of Shares PSUs - IPO Incentive Awards PSUs - 2019 LTI RSUs Stock Options 2018 Long Term Incentive Plan (LTIP) Unvested, beginning of period 555,163 391,136 1,353,852 1,374,945 870,471 Granted — — — — — Vested — — — — — Forfeited 11,967 8,809 33,015 — 14,372 Unvested, end of period 543,196 382,327 1,320,837 1,374,945 856,099

Common shareholder's equity, _2

Common shareholder's equity, mezzanine equity, and non-controlling interests (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Schedule of changes in the company's issued and outstanding common shares	The following table presents changes in the Company's issued and outstanding Common shares as of March 31, 2020 and 2019 , respectively: Three months ended March 31, (Millions) 2020 2019 Common shares: Shares issued and outstanding, beginning of period 115,299,341 115,151,251 Issuance of shares to directors and employees — 111,052 Shares issued and outstanding, end of period 115,299,341 115,262,303
Schedule of change in non-controlling interest	The following tables show the change in non-controlling interest for the three months ended March 31, 2020 and 2019 : (Millions) For the three months ended March 31, 2020 For the three months ended March 31, 2019 Non-controlling interests, beginning of the period $ 2.4 $ 1.7 Net income attributable to non-controlling interests 0.2 0.4 Other, net — 0.1 Non-controlling interests, end of the period $ 2.6 $ 2.2

Earnings per share (Tables)

Earnings per share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted earnings per common share	The following table sets forth the computation of basic and diluted earnings per common share for the three months ended March 31, 2020 and 2019 : For the three months ended March 31, (Millions, except share and per share information) 2020 2019 Basic earnings per share Numerator: Net income $ (121.3 ) $ 104.1 Less: Income attributable to non-controlling interests (0.2 ) (0.4 ) Less: Change in carrying value of Series B preference shares 23.4 (8.4 ) Net income available for dividends out of undistributed earnings $ (98.1 ) $ 95.3 Less: Earnings attributable to Series B preference shares — (8.9 ) Net income available to Sirius Group common shareholders $ (98.1 ) $ 86.4 Denominator: Weighted average shares outstanding for basic earnings per share 115,262,302 115,182,331 Basic earnings per share $ (0.85 ) $ 0.75 Diluted earnings per share Numerator: Net income available to Sirius Group common shareholders $ (98.1 ) $ 86.4 Add: Change in carrying value of Series B preference shares (23.4 ) 8.4 Net income available to Sirius Group common shareholders on a diluted basis $ (121.5 ) $ 94.8 Denominator: Weighted average shares outstanding for basic earnings per share 115,262,302 115,182,331 Add: Series B preference shares 11,901,670 11,901,670 Add: Unvested performance share units and restricted share units — 251,313 Weighted average shares outstanding for diluted earnings per share (1) 127,163,972 127,335,314 Diluted earnings per share $ (0.96 ) $ 0.74 (1) For the three months ended March 31, 2020 , there were a total of 15,972,398 potentially dilutive securities excluded from the calculation of Diluted earnings per share. For the three months ended March 31, 2019 , there were 19,510,830 potentially dilutive securities excluded from the calculation of Diluted earnings per share.

Investments in unconsolidated_2

Investments in unconsolidated entities (Tables)	3 Months Ended
	Mar. 31, 2020
Investments in unconsolidated entities
Schedule of components of Other long-term investments	The following table presents the components of Other long-term investments as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Equity method eligible unconsolidated entities, at fair value $ 151.8 $ 151.9 Other unconsolidated investments, at fair value (1) 203.7 194.9 Total Other long-term investments (2) $ 355.5 $ 346.8 (1) Includes Other long-term investments that are not equity method eligible. (2) There were no investments accounted for using the equity method as of March 31, 2020 and December 31, 2019 .
Schedule of investments in equity method eligible unconsolidated entities	The following table presents Sirius Group's investments in equity method eligible unconsolidated entities as of March 31, 2020 and December 31, 2019 : Ownership interest as of Investee March 31, 2020 December 31, 2019 Instrument Held BE Reinsurance Limited 24.9 % 24.9 % Common shares BioVentures Investors (Offshore) IV LP 73.0 % 73.0 % Units Camden Partners Strategic Fund V (Cayman), LP 39.4 % 39.4 % Units Diamond LS I LP 16.0 % 16.0 % Units Gateway Fund LP 19.3 % 15.0 % Units Monarch 12.8 % 12.8 % Units New Energy Capital Infrastructure Credit Fund LP 30.5 % 30.5 % Units New Energy Capital Infrastructure Offshore Credit Fund LP 30.5 % 30.5 % Units Pie Preferred Stock (1) 30.1 % 30.1 % Preferred shares Pie Series B Preferred Stock (1) 22.4 % 22.4 % Preferred shares Quintana Energy Partners 21.8 % 21.8 % Units Tuckerman Capital V LP 48.3 % 48.3 % Units Tuckerman Capital V Co-Investment I LP 48.3 % 48.1 % Units (1) Sirius Group holds investments in several financing instruments of Pie Insurance Holding, Inc.

Variable interest entities (Tab

Variable interest entities (Tables)	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of assets and liabilities related to the consolidated VIEs	The following table presents Alstead Re's assets and liabilities, as classified in the Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019 : (Millions) March 31, 2020 December 31, 2019 Assets: Fixed maturity investments $ 3.6 $ 3.9 Short-term investments 0.5 0.5 Cash 0.1 0.1 Total investments 4.2 4.5 Insurance and reinsurance premiums receivable (0.5 ) (0.3 ) Funds held by ceding companies 3.4 3.4 Deferred acquisition costs 0.1 0.3 Other assets — — Total assets $ 7.2 $ 7.9 Liabilities Loss and loss adjustment expense reserves $ 0.4 $ 0.5 Unearned insurance and reinsurance premiums 0.1 0.6 Other liabilities 0.1 0.1 Total liabilities $ 0.6 $ 1.2
Schedule of total assets of unconsolidated VIEs	The following table presents total assets of unconsolidated VIEs in which Sirius Group holds a variable interest, as well as the maximum exposure to loss associated with these VIEs: Maximum Exposure to Loss (Millions) Total VIE Assets On-Balance Sheet Off-Balance Sheet Total March 31, 2020 Other long-term investments (1) $ 250.7 $ 103.0 $ 8.8 $ 111.8 Total at March 31, 2020 $ 250.7 $ 103.0 $ 8.8 $ 111.8 December 31, 2019 Other long-term investments (1) $ 257.8 $ 102.6 $ 16.3 $ 118.9 Total at December 31, 2019 $ 257.8 $ 102.6 $ 16.3 $ 118.9 (1) Comprised primarily of hedge funds and private equity funds.

Commitments and contingencies (

Commitments and contingencies (Tables)	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of lease balances within the Consolidated Balance Sheets	The following table presents the lease balances within the Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019 : (millions) Balance Sheet Classification March 31, 2020 December 31, 2019 Operating lease right-of-use assets Other assets $26.1 $27.4 Current lease liabilities Other liabilities $7.6 $8.3 Non-current lease liabilities Other liabilities $20.2 $21.0
Schedule of weighted average remaining lease term and weighted average discount rate	The following table presents weighted average remaining lease term and weighted average discount rate as of March 31, 2020 : Weighted average lease term (years) as at March 31, 2020 Leased offices 7 years Leased equipment 3 years Weighted average discount rate: Leased offices 3.6 % Leased equipment 3.4 %
Schedule of future annual minimum rental payments required under non cancellable leases for office space	The following table presents future annual minimum rental payments required under non-cancellable leases and the present value discount to arrive at total lease liability as of March 31, 2020 : (Millions) Future Payments 2020 $ 6.5 2021 8.1 2022 7.2 2023 4.7 2024 2.3 2025 and after 1.1 Total future annual minimum rental payments as of March 31, 2020 29.9 Less: present value discount (2.1 ) Total lease liability as of March 31, 2020 $ 27.8

Summary of significant accoun_3

Summary of significant accounting policies - Recent adopted changes in accounting principle and Recent accounting pronouncements (Details) - Accounting Standards Update 2016-13 $ in Millions	Jan. 01, 2020USD ($)
Summary of significant accounting policies
Allowance for credit loss upon adoption of new accounting guidance	$ (6.8)
Cumulative effect of an accounting change	$ 14.9

Significant transactions - Loss

Significant transactions - Loss portfolio transfer (Details) $ in Millions	Jan. 23, 2020USD ($)
Significant transactions
Cash received in loss portfolio transfer agreement	$ 69.7

Segment information - Segment r

Segment information - Segment results (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)productsegment	Mar. 31, 2019USD ($)
Segment information
Number of reportable segments | segment	4
Gross written premiums	$ 817.6	$ 622.3
Net written premiums	629.9	484.8
Net earned insurance and reinsurance premiums	434.7	311.9
Loss and allocated LAE	(414.1)	(174.5)
Insurance and reinsurance acquisition expenses	(74.7)	(63.3)
Technical profit	(54.1)	74.1
Unallocated LAE	(13)	(9.4)
Other underwriting expenses	(38)	(35.3)
Underwriting income (loss)	(105.1)	29.4
Service fee revenue	24.9	25.3
General and administrative expenses, MGU plus Runoff & Other	(32.1)	(24.4)
Underwriting (loss) income, including net service fee income	(95.9)	37.7
Net investment income	13.5	20.1
Net realized investment (losses) gains	20.3	9
Net unrealized investment (losses) gains	(43.8)	74
Net foreign exchange gains (losses)	18.5	5.1
Other revenue	(20.6)	(5.7)
General and administrative expenses	(16.4)	(7.4)
Intangible asset amortization expenses	(3.9)	(3.9)
Interest expense on debt	(7.8)	(7.6)
Pre-tax (loss) income	$ (136.1)	$ 121.3
Underwriting Ratios
Loss ratio	98.30%	59.00%
Acquisition expense ratio	17.20%	20.30%
Other underwriting expense ratio	8.70%	11.30%
Combined ratio	124.20%	90.60%
Goodwill and intangible assets	$ 576.7	$ 592.3
Managing general underwriters
Segment information
General and administrative expenses, MGU plus Runoff & Other	(15.7)	(17)
Corporate Elimination
Segment information
Insurance and reinsurance acquisition expenses	10.4	10.3
Technical profit	10.4	10.3
Unallocated LAE	(5.4)	(3.4)
Other underwriting expenses	(5)	(2.7)
Underwriting income (loss)	0	4.2
Service fee revenue	(11)	(11)
Corporate Elimination | Managing general underwriters
Segment information
Unallocated LAE	6	4.1
Other underwriting expenses	5	2.7
Global Reinsurance | Reportable segments
Segment information
Gross written premiums	465.3	435
Net written premiums	345.4	335.9
Net earned insurance and reinsurance premiums	235	211.3
Loss and allocated LAE	(257.2)	(107.8)
Insurance and reinsurance acquisition expenses	(50.9)	(45.6)
Technical profit	(73.1)	57.9
Unallocated LAE	(5)	(4)
Other underwriting expenses	(21.3)	(21.6)
Underwriting income (loss)	(99.4)	32.3
Underwriting (loss) income, including net service fee income	$ (99.4)	$ 32.3
Underwriting Ratios
Loss ratio	111.60%	52.90%
Acquisition expense ratio	21.70%	21.60%
Other underwriting expense ratio	9.10%	10.20%
Combined ratio	142.40%	84.70%
Global A&H | Reportable segments
Segment information
Gross written premiums	$ 262.1	$ 169.3
Net written premiums	200.7	134.9
Net earned insurance and reinsurance premiums	117.9	96.1
Loss and allocated LAE	(80.3)	(63.2)
Insurance and reinsurance acquisition expenses	(30.8)	(26.6)
Technical profit	6.8	6.3
Unallocated LAE	(1.7)	(1.5)
Other underwriting expenses	(5.6)	(6.1)
Underwriting income (loss)	(0.5)	(1.3)
Service fee revenue	35.9	36.3
Underwriting (loss) income, including net service fee income	$ 10.2	$ 12
Underwriting Ratios
Loss ratio	69.60%	67.30%
Acquisition expense ratio	26.10%	27.70%
Other underwriting expense ratio	4.70%	6.30%
Combined ratio	100.40%	101.30%
Goodwill and intangible assets	$ 568.6	$ 584.2
Global A&H | Reportable segments | Managing general underwriters
Segment information
Unallocated LAE	(6)	(4.1)
Other underwriting expenses	(5)	(2.7)
General and administrative expenses, MGU plus Runoff & Other	$ (14.2)	(16.2)
U.S. Specialty
Underwriting Ratios
Number of Core Products | product	4
U.S. Specialty | Reportable segments
Segment information
Gross written premiums	$ 20.8	16.6
Net written premiums	15.2	13.6
Net earned insurance and reinsurance premiums	12.8	4.1
Loss and allocated LAE	(7.7)	(2.4)
Insurance and reinsurance acquisition expenses	(3)	(0.7)
Technical profit	2.1	1
Unallocated LAE	(0.1)	0
Other underwriting expenses	(5.2)	(2.8)
Underwriting income (loss)	(3.2)	(1.8)
Underwriting (loss) income, including net service fee income	$ (3.2)	$ (1.8)
Underwriting Ratios
Loss ratio	60.90%	58.50%
Acquisition expense ratio	23.40%	17.10%
Other underwriting expense ratio	40.60%	68.30%
Combined ratio	124.90%	143.90%
U.S. Specialty | Reportable segments | Minimum
Segment information
Pre-agreed domestic and export sales of goods and services coverage period	60 days
U.S. Specialty | Reportable segments | Maximum
Segment information
Pre-agreed domestic and export sales of goods and services coverage period	120 days
Runoff & Other | Reportable segments
Segment information
Gross written premiums	$ 69.4	$ 1.4
Net written premiums	68.6	0.4
Net earned insurance and reinsurance premiums	69	0.4
Loss and allocated LAE	(68.9)	(1.1)
Insurance and reinsurance acquisition expenses	(0.4)	(0.7)
Technical profit	(0.3)	(1.4)
Unallocated LAE	(0.8)	(0.5)
Other underwriting expenses	(0.9)	(2.1)
Underwriting income (loss)	(2)	(4)
Underwriting (loss) income, including net service fee income	(3.5)	(4.8)
Underwriting Ratios
Goodwill and intangible assets	8.1	8.1
Runoff & Other | Reportable segments | Managing general underwriters
Segment information
General and administrative expenses, MGU plus Runoff & Other	$ (1.5)	$ (0.8)

Segment information - Net premi

Segment information - Net premiums written by client location and underwriting location by reportable segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	$ 629.9	$ 484.8
Client location: United States
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	368.3	241.5
Client location: Europe
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	180.3	157.6
Client location: Canada, the Caribbean, Bermuda and Latin America
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	35.9	34
Client location: Asia and Other
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	45.4	51.7
Underwriting location: United States
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	287	160.5
Underwriting location: Europe
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	278.1	270.7
Underwriting location: Canada, the Caribbean, Bermuda and Latin America
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	48.1	35.9
Underwriting location: Asia and Other
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	16.7	17.7
Global Reinsurance | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	345.4	335.9
Global Reinsurance | Client location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	104.3	116.6
Global Reinsurance | Client location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	172.8	149.5
Global Reinsurance | Client location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	29.4	29
Global Reinsurance | Client location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	38.9	40.8
Global Reinsurance | Underwriting location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	72.6	75.7
Global Reinsurance | Underwriting location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	208.2	207
Global Reinsurance | Underwriting location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	48.1	35.9
Global Reinsurance | Underwriting location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	16.5	17.3
Global A&H | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	200.7	134.9
Global A&H | Client location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	180.7	111.1
Global A&H | Client location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	7.2	8
Global A&H | Client location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	6.5	5
Global A&H | Client location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	6.3	10.8
Global A&H | Underwriting location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	131.2	71
Global A&H | Underwriting location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	69.5	63.6
Global A&H | Underwriting location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
Global A&H | Underwriting location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0.3
U.S. Specialty | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	15.2	13.6
U.S. Specialty | Client location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	15.2	13.6
U.S. Specialty | Client location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
U.S. Specialty | Client location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
U.S. Specialty | Client location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
U.S. Specialty | Underwriting location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	15.2	13.6
U.S. Specialty | Underwriting location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
U.S. Specialty | Underwriting location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
U.S. Specialty | Underwriting location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
Runoff & Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	68.6	0.4
Runoff & Other | Client location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	68.1	0.2
Runoff & Other | Client location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0.3	0.1
Runoff & Other | Client location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
Runoff & Other | Client location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0.2	0.1
Runoff & Other | Underwriting location: United States | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	68	0.2
Runoff & Other | Underwriting location: Europe | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0.4	0.1
Runoff & Other | Underwriting location: Canada, the Caribbean, Bermuda and Latin America | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	0	0
Runoff & Other | Underwriting location: Asia and Other | Reportable segments
Net premiums written by client location and underwriting location by reportable segment
Net written premiums	$ 0.2	$ 0.1

Reserves for unpaid losses an_3

Reserves for unpaid losses and loss adjustment expenses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Summary of the loss and LAE reserve activities
Gross beginning balance	$ 2,331.5	$ 2,016.7
Less beginning reinsurance recoverable on unpaid losses	(410.3)	(350.2)
Net loss and LAE reserve balance	1,921.2	1,666.5
Losses and LAE incurred relating to:
Current year losses	422.9	167.3
Prior years losses	4.2	16.6
Total net incurred losses and LAE	427.1	183.9
Foreign currency translation adjustment to net loss and LAE reserves	(21.8)	(3.4)
Loss and LAE paid relating to:
Current year losses	43.1	36.2
Prior years losses	208	183.8
Total loss and LAE payments	251.1	220
Net ending balance	2,075.4	1,627
Plus ending reinsurance recoverable on unpaid losses	444.2	349.3
Gross ending balance	$ 2,519.6	$ 1,976.3

Reserves for unpaid losses an_4

Reserves for unpaid losses and loss adjustment expenses - By segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reserves for unpaid losses and loss adjustment expenses
Prior years losses	$ 4.2	$ 16.6
Natural catastrophes
Reserves for unpaid losses and loss adjustment expenses
Prior years losses		15.6
Global Reinsurance
Reserves for unpaid losses and loss adjustment expenses
Prior years losses	9.1	10.3
Global A&H
Reserves for unpaid losses and loss adjustment expenses
Prior years losses	$ (4.2)	5.1
Runoff & Other
Reserves for unpaid losses and loss adjustment expenses
Prior years losses		$ 1.2

Third party reinsurance (Detail

Third party reinsurance (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Insurance [Abstract]
Reinsurance recoverable on paid losses	$ 85.7	$ 73.9
Reinsurance recoverable on unpaid losses	$ 444.2	$ 410.3

Allowance for expected credit_3

Allowance for expected credit losses (Details) $ in Millions	Mar. 31, 2020USD ($)
Ceded Credit Risk [Line Items]
Premiums receivable & Funds held by ceding companies	$ 1,224.7
Reinsurance recoverable on unpaid and paid loss	529.9
MGU Trade receivables	25.6
Total as of March 31, 2020	1,780.2
Premiums receivable & Funds held by ceding companies, allowance for credit losses	10.6
Reinsurance recoverable on unpaid and paid loss, allowance for credit losses	3.9
MGU trade receivable, allowance for credit losses	0.4
Total allowance for credit losses	$ 14.9
Percent of the total reinsurance recoverables rated by either A.M. Best or S&P	0.63
AM Best, A- Rating | Standard & Poor's, A- Rating
Ceded Credit Risk [Line Items]
Percent of the total reinsurance recoverables rated by either A.M. Best or S&P	0.76

Investment securities - Net inv

Investment securities - Net investment income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Investment Income
Total investment income	$ 16.4	$ 23.8
Investment expenses	(2.9)	(3.7)
Net investment income	13.5	20.1
Fixed maturity investments
Net Investment Income
Total investment income	10.3	16.8
Short-term investments
Net Investment Income
Total investment income	3.3	0.4
Equity securities
Net Investment Income
Total investment income	2.6	2.7
Other long-term investments
Net Investment Income
Total investment income	$ 0.2	$ 3.9

Investment securities - Net rea

Investment securities - Net realized and unrealized investment gains (losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net realized and unrealized investment gains (losses)
Gross realized gains	$ 42	$ 14.1
Gross realized (losses)	(21.7)	(5.1)
Net realized gains on investments	20.3	9
Net unrealized investment gains (losses)	(43.8)	74
Net realized and unrealized gains (losses) on investments	(23.5)	83
Realized gains due to foreign currency	11.1	10.9
Unrealized (losses) gains due to foreign currency	52.7	25
Total unrealized investment (losses) gains – Level 3 investments	(0.6)	8.8
Fixed maturity investments
Net realized and unrealized investment gains (losses)
Net realized gains on investments	7.8	6.8
Net unrealized investment gains (losses)	7.9	29.7
Total unrealized investment (losses) gains – Level 3 investments	0.3	0
Equity securities
Net realized and unrealized investment gains (losses)
Net realized gains on investments	0.5	(0.6)
Net unrealized investment gains (losses)	(69.1)	25.1
Total unrealized investment (losses) gains – Level 3 investments	0	0
Short-term investments
Net realized and unrealized investment gains (losses)
Net realized gains on investments	2.8	0.1
Net unrealized investment gains (losses)	15.7	2.7
Derivative instruments
Net realized and unrealized investment gains (losses)
Net realized gains on investments	8.3	(0.6)
Net unrealized investment gains (losses)	0.1	(0.6)
Other long-term investments
Net realized and unrealized investment gains (losses)
Net realized gains on investments	0.9	3.3
Net unrealized investment gains (losses)	1.6	17.1
Total unrealized investment (losses) gains – Level 3 investments	$ (0.9)	$ 8.8

Investment securities - Fixed m

Investment securities - Fixed maturity investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Fixed maturity investments
Cost or amortized cost	$ 1,705	$ 1,656.6
Gross unrealized gains	37.5	18.7
Gross unrealized losses	(42)	(8.2)
Net foreign currency gains (losses)	31.6	13.9
Fair value	$ 1,732.1	1,681
Weighted average duration of fixed income portfolio including short-term investments	1 year 6 months
Weighted average duration of fixed income portfolio excluding short-term investments	2 years 3 months
Cost or amortized cost
Due in one year or less	$ 106.2	85
Due after one year through five years	429.1	479.1
Due after five years through ten years	45.9	46.3
Due after ten years	25.2	25.1
Fair value
Due in one year or less	112.9	88.4
Due after one year through five years	446.3	490.3
Due after five years through ten years	47	46
Due after ten years	28.8	24.6
Fixed maturity investments
Fixed maturity investments
Fair value	1,732.1	1,681
Fixed maturity investments | AAA
Fixed maturity investments
Fair value	588.4	559.8
Fixed maturity investments | AA
Fixed maturity investments
Fair value	786.8	724.3
Fixed maturity investments | A
Fixed maturity investments
Fair value	208.5	219
Fixed maturity investments | BBB
Fixed maturity investments
Fair value	88	95.8
Fixed maturity investments | Other
Fixed maturity investments
Fair value	60.4	82.1
Corporate debt securities
Fixed maturity investments
Cost or amortized cost	424.5	458.6
Gross unrealized gains	2.8	5.2
Gross unrealized losses	(5)	(1.2)
Net foreign currency gains (losses)	22	11.5
Fair value	444.3	474.1
Asset-backed securities
Fixed maturity investments
Cost or amortized cost	551.9	489.4
Gross unrealized gains	1.9	1.4
Gross unrealized losses	(30.1)	(3.9)
Net foreign currency gains (losses)	0.7	(0.1)
Fair value	524.4	486.8
Residential mortgage-backed securities
Fixed maturity investments
Cost or amortized cost	443.5	426.2
Gross unrealized gains	23.1	10.5
Gross unrealized losses	(1.2)	(1.4)
Net foreign currency gains (losses)	6.5	3.6
Fair value	471.9	438.9
U.S. Government and government agency
Fixed maturity investments
Cost or amortized cost	119.9	111.5
Gross unrealized gains	6.8	0.7
Gross unrealized losses	(0.1)	(0.4)
Net foreign currency gains (losses)	1.6	(1.3)
Fair value	128.2	110.5
Commercial mortgage-backed securities
Fixed maturity investments
Cost or amortized cost	97.4	88.5
Gross unrealized gains	1.6	0.9
Gross unrealized losses	(5)	(0.6)
Net foreign currency gains (losses)	0.3	0.2
Fair value	94.3	89
Non-U.S. government and government agency
Fixed maturity investments
Cost or amortized cost	60.4	63.7
Gross unrealized gains	0.4	0
Gross unrealized losses	(0.4)	(0.7)
Net foreign currency gains (losses)	0.4	0
Fair value	60.8	63
Preferred stocks
Fixed maturity investments
Cost or amortized cost	5.8	17
Gross unrealized gains	0.9	0
Gross unrealized losses	(0.2)	0
Net foreign currency gains (losses)	0	0
Fair value	6.5	17
Cost or amortized cost
Cost or amortized cost without single maturity date	5.8	17
Fair value
Fair value without single maturity date	6.5	17
U.S. States, municipalities and political subdivision
Fixed maturity investments
Cost or amortized cost	1.6	1.7
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Net foreign currency gains (losses)	0.1	0
Fair value	1.7	1.7
Mortgage-backed and asset-backed securities
Cost or amortized cost
Cost or amortized cost without single maturity date	1,092.8	1,004.1
Fair value
Fair value without single maturity date	1,090.6	1,014.7
Subprime | Fixed maturity investments
Fixed maturity investments
Fair value	37.8	43.3
Subprime | Fixed maturity investments | AAA
Fixed maturity investments
Fair value	18.3	21.7
Subprime | Fixed maturity investments | AA
Fixed maturity investments
Fair value	17.2	18.4
Subprime | Fixed maturity investments | A
Fixed maturity investments
Fair value	2.2	3.1
Subprime | Fixed maturity investments | Other
Fixed maturity investments
Fair value	$ 0.1	$ 0.1

Investment securities - Equity

Investment securities - Equity securities and Other long-term investments (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Equity securities
Equity securities and Other long-term investments
Cost or amortized cost	$ 409.5	$ 379.2
Gross unrealized gains	37.4	55.6
Gross unrealized losses	(98.4)	(37.3)
Net foreign currency gains	18.1	7.7
Fair value	366.6	405.2
Other long-term investments
Equity securities and Other long-term investments
Cost or amortized cost	323.2	315.4
Gross unrealized gains	50.3	49.9
Gross unrealized losses	(31.7)	(29.3)
Net foreign currency gains	13.7	10.8
Fair value	355.5	346.8
Other long-term investments | Hedge funds and private equity funds
Equity securities and Other long-term investments
Fair value	279.6	269
Other long-term investments | Limited liability companies and private equity securities
Equity securities and Other long-term investments
Fair value	75.9	77.8
Fixed income mutual funds
Equity securities and Other long-term investments
Fair value	192.1	175.3
Common shares
Equity securities and Other long-term investments
Fair value	184.4	228.1
Other equity securities
Equity securities and Other long-term investments
Fair value	$ (9.9)	$ 1.8

Investment securities - Hedge f

Investment securities - Hedge funds and Private equity funds (Details) - Other long-term investments $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)fund	Dec. 31, 2019USD ($)
Equity securities and Other long-term investments
Fair value	$ 355.5	$ 346.8
Hedge funds and private equity funds
Equity securities and Other long-term investments
Fair value	279.6	269
Unfunded commitments	$ 51.3	60.1
Hedge funds:
Equity securities and Other long-term investments
Number of investment funds in which the investments are held | fund	9
Fair value	$ 131.8	127.5
Unfunded commitments	0	0
Long/short multi-sector
Equity securities and Other long-term investments
Fair value	49.5	53
Unfunded commitments	0	0
Distressed mortgage credit
Equity securities and Other long-term investments
Fair value	59.4	51.6
Unfunded commitments	0	0
Private credit
Equity securities and Other long-term investments
Fair value	21.8	21.5
Unfunded commitments	0	0
Other
Equity securities and Other long-term investments
Fair value	1.1	1.4
Unfunded commitments	$ 0	0
Private equity funds:
Equity securities and Other long-term investments
Number of investment funds in which the investments are held | fund	33
Fair value	$ 147.8	141.5
Unfunded commitments	51.3	60.1
Energy infrastructure & services
Equity securities and Other long-term investments
Fair value	51.5	53.6
Unfunded commitments	34.1	34.6
Multi-sector
Equity securities and Other long-term investments
Fair value	16	8.7
Unfunded commitments	7.8	7.8
Healthcare
Equity securities and Other long-term investments
Fair value	28.2	25.9
Unfunded commitments	6.8	10.4
Life settlement
Equity securities and Other long-term investments
Fair value	22.9	23.9
Unfunded commitments	0	0
Manufacturing/Industrial
Equity securities and Other long-term investments
Fair value	26.3	27.6
Unfunded commitments	0	3.9
Private equity secondaries
Equity securities and Other long-term investments
Fair value	0.6	0.6
Unfunded commitments	0.8	0.8
Other
Equity securities and Other long-term investments
Fair value	2.3	1.2
Unfunded commitments	$ 1.8	$ 2.6

Investment securities - Hedge_2

Investment securities - Hedge Funds redemption frequency and Private Equity Fund lock-up period (Details) - Other long-term investments - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Equity securities and Other long-term investments
Fair value	$ 355.5	$ 346.8
Hedge funds:
Equity securities and Other long-term investments
Fair value	131.8	127.5
Hedge funds: | Monthly Redemption Frequency
Equity securities and Other long-term investments
Fair value	33.5
Hedge funds: | Quarterly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0.6
Hedge funds: | Semi-annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	0.2
Hedge funds: | Annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	97.5
Private equity funds:
Equity securities and Other long-term investments
Fair value	147.8	$ 141.5
Private equity funds: | Lock up period of 1 - 3 years
Equity securities and Other long-term investments
Fair value	9.1
Private equity funds: | Lock up period of 3 - 5 years
Equity securities and Other long-term investments
Fair value	2.1
Private equity funds: | Lock up period of 5 - 10 years
Equity securities and Other long-term investments
Fair value	136.6
30-59 days notice | Hedge funds:
Equity securities and Other long-term investments
Fair value	0.6
30-59 days notice | Hedge funds: | Monthly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
30-59 days notice | Hedge funds: | Quarterly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0.6
30-59 days notice | Hedge funds: | Semi-annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
30-59 days notice | Hedge funds: | Annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
60-89 days notice | Hedge funds:
Equity securities and Other long-term investments
Fair value	49.7
60-89 days notice | Hedge funds: | Monthly Redemption Frequency
Equity securities and Other long-term investments
Fair value	33.5
60-89 days notice | Hedge funds: | Quarterly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
60-89 days notice | Hedge funds: | Semi-annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	0.2
60-89 days notice | Hedge funds: | Annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	16
90-119 days notice | Hedge funds:
Equity securities and Other long-term investments
Fair value	59.6
90-119 days notice | Hedge funds: | Monthly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
90-119 days notice | Hedge funds: | Quarterly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
90-119 days notice | Hedge funds: | Semi-annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
90-119 days notice | Hedge funds: | Annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	59.6
120+ days notice | Hedge funds:
Equity securities and Other long-term investments
Fair value	21.9
120+ days notice | Hedge funds: | Monthly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
120+ days notice | Hedge funds: | Quarterly Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
120+ days notice | Hedge funds: | Semi-annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	0
120+ days notice | Hedge funds: | Annual Redemption Frequency
Equity securities and Other long-term investments
Fair value	$ 21.9

Investment securities - Investm

Investment securities - Investments held on deposit or as collateral and Unsettled investment purchases and sales (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Marketable securities
Investments held in trusts	$ 971.1	$ 1,309.5
Investments held in trusts - fair value	1,002.8	1,315.5
Accounts payable
Marketable securities
Unsettled investment purchases	53	2.3
Accounts receivable
Marketable securities
Unsettled investment sales	35.2	6.7
Interest rate cap | Derivatives not designated as hedging instruments
Marketable securities
Collateral balances held	$ 0.2	$ 0.2

Fair value measurements - Fair

Fair value measurements - Fair value measurements by level (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets measured at fair value
Fixed maturity investments	$ 1,732.1	$ 1,681
Equity securities	366.6	405.2
Short-term investments	1,041.8	1,085.2
Other long-term investments	75.9	77.8
Total investments	3,216.4	3,249.2
Derivative instruments	11.7	11.4
Total assets measured at fair value	3,248	3,280.6
Liabilities measured at fair value
Contingent consideration liabilities	28.3	28.2
Derivative instruments	20.4	9.5
Total liabilities measured at fair value	48.7	37.7
U.S. Government and government agency
Assets measured at fair value
Fixed maturity investments	128.2	110.5
Corporate debt securities
Assets measured at fair value
Fixed maturity investments	444.3	474.1
Residential mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	471.9	438.9
Asset-backed securities
Assets measured at fair value
Fixed maturity investments	524.4	486.8
Commercial mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	94.3	89
Non-U.S. government and government agency
Assets measured at fair value
Fixed maturity investments	60.8	63
Preferred stocks
Assets measured at fair value
Fixed maturity investments	6.5	17
U.S. States, municipalities, and political subdivision
Assets measured at fair value
Fixed maturity investments	1.7	1.7
Fixed income mutual funds
Assets measured at fair value
Equity securities	192.1	175.3
Common shares
Assets measured at fair value
Equity securities	184.4	228.1
Other equity securities
Assets measured at fair value
Equity securities	(9.9)	1.8
Level 1 Inputs
Assets measured at fair value
Fixed maturity investments	156.8	140.8
Equity securities	364.9	403.4
Short-term investments	1,019.5	1,073.7
Other long-term investments	0	0
Total investments	1,541.2	1,617.9
Derivative instruments	1	1.3
Total assets measured at fair value	1,542.2	1,619.2
Liabilities measured at fair value
Contingent consideration liabilities	0	0
Derivative instruments	0.8	0.2
Total liabilities measured at fair value	0.8	0.2
Level 1 Inputs | U.S. Government and government agency
Assets measured at fair value
Fixed maturity investments	127.1	109.1
Level 1 Inputs | Corporate debt securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 1 Inputs | Residential mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 1 Inputs | Asset-backed securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 1 Inputs | Commercial mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 1 Inputs | Non-U.S. government and government agency
Assets measured at fair value
Fixed maturity investments	29.7	31.7
Level 1 Inputs | Preferred stocks
Assets measured at fair value
Fixed maturity investments	0	0
Level 1 Inputs | U.S. States, municipalities, and political subdivision
Assets measured at fair value
Fixed maturity investments	0	0
Level 1 Inputs | Fixed income mutual funds
Assets measured at fair value
Equity securities	192.1	175.3
Level 1 Inputs | Common shares
Assets measured at fair value
Equity securities	184.4	228.1
Level 1 Inputs | Other equity securities
Assets measured at fair value
Equity securities	(11.6)	0
Level 2 Inputs
Assets measured at fair value
Fixed maturity investments	1,572.7	1,523.2
Equity securities	1.7	1.8
Short-term investments	22.3	11.5
Other long-term investments	0	0
Total investments	1,596.7	1,536.5
Derivative instruments	0	0
Total assets measured at fair value	1,596.7	1,536.5
Liabilities measured at fair value
Contingent consideration liabilities	0	0
Derivative instruments	0	0
Total liabilities measured at fair value	0	0
Level 2 Inputs | U.S. Government and government agency
Assets measured at fair value
Fixed maturity investments	1.1	1.4
Level 2 Inputs | Corporate debt securities
Assets measured at fair value
Fixed maturity investments	444.3	474.1
Level 2 Inputs | Residential mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	471.9	438.9
Level 2 Inputs | Asset-backed securities
Assets measured at fair value
Fixed maturity investments	524.4	486.8
Level 2 Inputs | Commercial mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	94.3	89
Level 2 Inputs | Non-U.S. government and government agency
Assets measured at fair value
Fixed maturity investments	31.1	31.3
Level 2 Inputs | Preferred stocks
Assets measured at fair value
Fixed maturity investments	3.9	0
Level 2 Inputs | U.S. States, municipalities, and political subdivision
Assets measured at fair value
Fixed maturity investments	1.7	1.7
Level 2 Inputs | Fixed income mutual funds
Assets measured at fair value
Equity securities	0	0
Level 2 Inputs | Common shares
Assets measured at fair value
Equity securities	0	0
Level 2 Inputs | Other equity securities
Assets measured at fair value
Equity securities	1.7	1.8
Level 3 Inputs
Assets measured at fair value
Fixed maturity investments	2.6	17
Equity securities	0	0
Short-term investments	0	0
Other long-term investments	75.9	77.8
Total investments	78.5	94.8
Derivative instruments	10.7	10.1
Total assets measured at fair value	109.1	124.9
Liabilities measured at fair value
Contingent consideration liabilities	28.3	28.2
Derivative instruments	19.6	9.3
Total liabilities measured at fair value	47.9	37.5
Level 3 Inputs | U.S. Government and government agency
Assets measured at fair value
Fixed maturity investments	0	0
Level 3 Inputs | Corporate debt securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 3 Inputs | Residential mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 3 Inputs | Asset-backed securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 3 Inputs | Commercial mortgage-backed securities
Assets measured at fair value
Fixed maturity investments	0	0
Level 3 Inputs | Non-U.S. government and government agency
Assets measured at fair value
Fixed maturity investments	0	0
Level 3 Inputs | Preferred stocks
Assets measured at fair value
Fixed maturity investments	2.6	17
Level 3 Inputs | U.S. States, municipalities, and political subdivision
Assets measured at fair value
Fixed maturity investments	0	0
Level 3 Inputs | Fixed income mutual funds
Assets measured at fair value
Equity securities	0	0
Level 3 Inputs | Common shares
Assets measured at fair value
Equity securities	0	0
Level 3 Inputs | Other equity securities
Assets measured at fair value
Equity securities	0	0
Loan participation
Assets measured at fair value
Loan participation	19.9	20
Loan participation | Level 1 Inputs
Assets measured at fair value
Loan participation	0	0
Loan participation | Level 2 Inputs
Assets measured at fair value
Loan participation	0	0
Loan participation | Level 3 Inputs
Assets measured at fair value
Loan participation	$ 19.9	$ 20

Fair value measurements - Rollf

Fair value measurements - Rollforward of level 3 fair value measurements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Rollforward of Level 3, Derivative instruments assets & (liabilities)
Balance at beginning of the period	$ 0.8	$ (0.5)
Total realized and unrealized gains (losses)	(13.3)	(5.1)
Purchases	0	0
Sales/Settlements	3.6	0.8
Balance at end of the period	(8.9)	(4.8)
Hedge funds and private equity funds
Rollforward of Level 3, (liabilities)
Fair value of hedges	279.6	301.7	$ 269
Fixed maturity investments
Rollforward of Level 3 Fair Value Measurements
Balance at beginning of the period	17	5.4
Total realized and unrealized gains (losses)	2.6	0
Purchases	0	0
Sales/Settlements	(17)	(5.4)
Balance at end of the period	2.6	0
Other long-term investments
Rollforward of Level 3 Fair Value Measurements
Balance at beginning of the period	77.8	63.6
Total realized and unrealized gains (losses)	(0.9)	9.3
Purchases	0	15.8
Sales/Settlements	0	0
Balance at end of the period	75.9	88
Loan participation
Rollforward of Level 3 Fair Value Measurements
Balance at beginning of the period	20	0
Total realized and unrealized gains (losses)	0	0
Purchases	0	0
Sales/Settlements	(0.1)	0
Balance at end of the period	19.9	0
Contingent consideration (liabilities)
Rollforward of Level 3, (liabilities)
Balance at beginning of the period	(28.2)	(28.8)
Total realized and unrealized gains (losses)	(0.1)	0
Foreign currency gains (losses) through Other Comprehensive Income	0	0
Purchases	0	0
Sales/Settlements	0	0
Balance at end of the period	(28.3)	(28.8)
Other Comprehensive Income Foreign Currency Gain Loss [Member]
Rollforward of Level 3, Derivative instruments assets & (liabilities)
Foreign currency gains (losses) through Other Comprehensive Income	0	0
Other Comprehensive Income Foreign Currency Gain Loss [Member] | Fixed maturity investments
Rollforward of Level 3 Fair Value Measurements
Gains (losses) through Other Comprehensive Income	0	0
Other Comprehensive Income Foreign Currency Gain Loss [Member] | Other long-term investments
Rollforward of Level 3 Fair Value Measurements
Gains (losses) through Other Comprehensive Income	(1)	(0.7)
Other Comprehensive Income Foreign Currency Gain Loss [Member] | Loan participation
Rollforward of Level 3 Fair Value Measurements
Gains (losses) through Other Comprehensive Income	$ 0	$ 0

Fair value measurements - Signi

Fair value measurements - Significant unobservable inputs (Details) $ in Thousands	Mar. 31, 2020USD ($)$ / shares	Dec. 31, 2019USD ($)$ / shares
Significant Unobservable Inputs
Equity securities	$ 366,600	$ 405,200
Derivative assets	11,700	11,400
Derivative liabilities	(20,400)	(9,500)
Contingent consideration	(28,300)	(28,200)
Level 3 Inputs
Significant Unobservable Inputs
Equity securities	0	0
Derivative assets	10,700	10,100
Derivative liabilities	(19,600)	(9,300)
Contingent consideration	(28,300)	(28,200)
Level 3 Inputs | Share price of recent transaction | Private equity securities
Significant Unobservable Inputs
Equity securities	32,500	32,500
Level 3 Inputs | Share price of recent transaction | Preferred stock
Significant Unobservable Inputs
Equity securities	$ 17,500	$ 17,500
Level 3 Inputs | Share price of recent transaction | Purchase share price | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input | $ / shares	40.6	40.6
Level 3 Inputs | Share price of recent transaction | Purchase price | Preferred stock
Significant Unobservable Inputs
Equity securities, measurement input | $ / shares	7.74	7.74
Level 3 Inputs | Purchase price of recent transaction | Loan participation
Significant Unobservable Inputs
Equity securities	$ 19,900	$ 20,000
Equity securities, measurement input		20,000
Level 3 Inputs | Purchase price of recent transaction | Private debt instrument
Significant Unobservable Inputs
Debt securities, trading	6,200	$ 7,200
Level 3 Inputs | Purchase price of recent transaction | Private equity securities
Significant Unobservable Inputs
Equity securities	5,100	300
Level 3 Inputs | Purchase price of recent transaction | Preferred stock
Significant Unobservable Inputs
Equity securities	1,900	12,200
Level 3 Inputs | Purchase price of recent transaction | Private equity funds
Significant Unobservable Inputs
Equity securities	1,000	5,100
Level 3 Inputs | Purchase price of recent transaction | Preferred stock
Significant Unobservable Inputs
Equity securities	700	4,800
Level 3 Inputs | Purchase price of recent transaction | Private equity securities
Significant Unobservable Inputs
Equity securities	$ 300
Level 3 Inputs | Purchase price of recent transaction | Private equity securities
Significant Unobservable Inputs
Equity securities		1,000
Level 3 Inputs | Purchase price of recent transaction | Purchase price | Private debt instrument
Significant Unobservable Inputs
Private debt instrument, measurement input, value		9,000
Level 3 Inputs | Purchase price of recent transaction | Purchase price | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input, value		300
Equity securities, measurement input | $ / shares	7.74
Level 3 Inputs | Purchase price of recent transaction | Purchase price | Preferred stock
Significant Unobservable Inputs
Equity securities, measurement input, value	$ 1,900	$ 12,200
Level 3 Inputs | Purchase price of recent transaction | Purchase price | Private equity funds
Significant Unobservable Inputs
Equity securities, measurement input, value	0
Equity securities, measurement input | $ / shares		7.74
Level 3 Inputs | Purchase price of recent transaction | Purchase price | Preferred stock
Significant Unobservable Inputs
Equity securities, measurement input, value	700	$ 4,800
Level 3 Inputs | Purchase price of recent transaction | Purchase price | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input, value	300
Level 3 Inputs | Purchase price of recent transaction | Purchase price | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input | $ / shares		10
Level 3 Inputs | Multiple of GAAP book value | Private equity securities
Significant Unobservable Inputs
Equity securities	13,300	$ 14,200
Level 3 Inputs | Multiple of GAAP book value | Book value multiple | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input | $ / shares		0.9
Level 3 Inputs | Third party appraisal | Weather derivatives
Significant Unobservable Inputs
Derivative assets		$ 7,000
Derivative liabilities	(13,900)
Level 3 Inputs | Third party appraisal | Currency forwards
Significant Unobservable Inputs
Derivative assets	1,700	(2,700)
Level 3 Inputs | Third party appraisal | Foreign currency swaps
Significant Unobservable Inputs
Derivative assets	2,400
Derivative liabilities		(3,600)
Level 3 Inputs | Third party appraisal | Currency forwards
Significant Unobservable Inputs
Derivative liabilities		(5,700)
Level 3 Inputs | Third party appraisal | Broker quote | Weather derivatives
Significant Unobservable Inputs
Derivative assets, measurement input, value		7,000
Derivative liabilities, measurement input, value	(13,900)
Level 3 Inputs | Third party appraisal | Broker quote | Currency forwards
Significant Unobservable Inputs
Derivative assets, measurement input, value	(1,700)	2,700
Level 3 Inputs | Third party appraisal | Broker quote | Foreign currency swaps
Significant Unobservable Inputs
Derivative assets, measurement input, value	(2,400)
Derivative liabilities, measurement input, value		(3,600)
Level 3 Inputs | Third party appraisal | Broker quote | Currency forwards
Significant Unobservable Inputs
Derivative liabilities, measurement input, value		(5,700)
Level 3 Inputs | Option pricing model
Significant Unobservable Inputs
Equity securities	900	400
Level 3 Inputs | Option pricing model | Strike price
Significant Unobservable Inputs
Equity securities, measurement input, value	200	200
Level 3 Inputs | External valuation model
Significant Unobservable Inputs
Contingent consideration	(28,300)	(28,200)
Level 3 Inputs | External valuation model | Discounted future payments
Significant Unobservable Inputs
Contingent consideration, measurement input, value	$ (28,300)	$ (28,200)
Minimum | Level 3 Inputs | Purchase price of recent transaction | Comparable yields | Loan participation
Significant Unobservable Inputs
Equity securities, measurement input	0.04
Minimum | Level 3 Inputs | Purchase price of recent transaction | Discount yield | Private debt instrument
Significant Unobservable Inputs
Debt Securities, Trading, Measurement Input	0.1187
Minimum | Level 3 Inputs | Multiple of GAAP book value | Book value multiple | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input | $ / shares	0.73
Maximum | Level 3 Inputs | Purchase price of recent transaction | Comparable yields | Loan participation
Significant Unobservable Inputs
Equity securities, measurement input	0.07
Maximum | Level 3 Inputs | Purchase price of recent transaction | Discount yield | Private debt instrument
Significant Unobservable Inputs
Debt Securities, Trading, Measurement Input	0.1232
Maximum | Level 3 Inputs | Multiple of GAAP book value | Book value multiple | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input | $ / shares	0.91
Median | Level 3 Inputs | Purchase price of recent transaction | Comparable yields | Loan participation
Significant Unobservable Inputs
Equity securities, measurement input	0.06
Median | Level 3 Inputs | Purchase price of recent transaction | Discount yield | Private debt instrument
Significant Unobservable Inputs
Debt Securities, Trading, Measurement Input	0.1208
Median | Level 3 Inputs | Multiple of GAAP book value | Book value multiple | Private equity securities
Significant Unobservable Inputs
Equity securities, measurement input | $ / shares	0.82

Fair value measurements - Finan

Fair value measurements - Financial instruments disclosed, but not carried at fair value (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financial instruments not carried at fair value
Debt	$ 664.8	$ 685.2
Carrying Value | Series B preference shares
Financial instruments not carried at fair value
Redeemable preference shares	205	223
2017 SEK Subordinated Notes
Financial instruments not carried at fair value
Debt	270.6	291.2
2017 SEK Subordinated Notes | Carrying Value
Financial instruments not carried at fair value
Debt	270.6	291.2
2016 SIG Senior Notes
Financial instruments not carried at fair value
Debt	394.2	394
2016 SIG Senior Notes | Carrying Value
Financial instruments not carried at fair value
Debt	394.2	394
Level 3 Inputs | Fair Value | Series B preference shares
Financial instruments not carried at fair value
Redeemable preference shares	171.4	186.4
Level 3 Inputs | 2017 SEK Subordinated Notes | Fair Value
Financial instruments not carried at fair value
Debt	268.3	294.5
Level 3 Inputs | 2016 SIG Senior Notes | Fair Value
Financial instruments not carried at fair value
Debt	$ 394.9	$ 394.5

Debt and standby letters of c_3

Debt and standby letters of credit facilities (Details)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 22, 2017USD ($)	Sep. 22, 2017SEK (kr)	Nov. 01, 2016USD ($)
Debt and standby letters of credit facilities
Long-term Debt, Total	$ 664,800,000	$ 685,200,000
2017 SEK Subordinated Notes
Debt and standby letters of credit facilities
Debt, at face value	274,200,000	295,000,000	$ 346,100,000	kr 2,750,000,000
Unamortized issuance costs	(3,600,000)	(3,800,000)
Long-term Debt, Total	$ 270,600,000	$ 291,200,000
Effective rate	4.20%	4.00%
2016 SIG Senior Notes
Debt and standby letters of credit facilities
Debt, at face value	$ 400,000,000	$ 400,000,000			$ 400,000,000
Unamortized issuance costs	(3,600,000)	(3,700,000)
Unamortized discount	(2,200,000)	(2,300,000)
Long-term Debt, Total	$ 394,200,000	$ 394,000,000
Effective rate	4.70%	4.70%

Debt and standby letters of c_4

Debt and standby letters of credit facilities - 2017 SEK Subordinated Notes and 2016 SIG Senior Notes (Details)	Sep. 22, 2017USD ($)	Sep. 22, 2017SEK (kr)	Nov. 01, 2016USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Sep. 22, 2017SEK (kr)
Debt and standby letters of credit facilities
Interest expense on debt				$ 7,800,000	$ 7,600,000
2017 SEK Subordinated Notes
Debt and standby letters of credit facilities
Debt notes issued	$ 346,100,000			274,200,000		$ 295,000,000	kr 2,750,000,000
Issue price (as a percent)	100.00%	100.00%
Term of redemption following occurrence of Specified Event (in days)	90 days	90 days
Debt issuance costs	$ 4,600,000
Underwriting fees	$ 3,500,000	kr 27,500,000
Foreign currency exchange (losses) gains on remeasurement of debt				$ 20,600,000	$ 11,000,000
Effective rate				4.20%	3.70%
Interest expense on debt				$ 3,000,000	$ 2,800,000
Effective rate				4.20%		4.00%
2016 SIG Senior Notes
Debt and standby letters of credit facilities
Debt notes issued			$ 400,000,000	$ 400,000,000		$ 400,000,000
Issue price (as a percent)			99.209%
Debt issuance costs			$ 5,100,000
Underwriting fees			3,400,000
Interest expense on debt				$ 4,800,000	$ 4,800,000
Net proceeds			$ 392,400,000
Annual interest rate (as a percent)			4.60%
Effective rate				4.70%		4.70%

Debt and standby letters of c_5

Debt and standby letters of credit facilities - Standby Letter of Credit Facilities (Details) kr in Billions	Mar. 31, 2020USD ($)	Mar. 31, 2020SEK (kr)	Dec. 31, 2019USD ($)	Dec. 31, 2019SEK (kr)	Nov. 09, 2019USD ($)letter_of_credit
Standby Letter of Credit Facilities
Number of standby letter of credit agreements renewed | letter_of_credit					2
Other Secured Letter of Credit and Trust Arrangement | Sirius America Insurance Company
Standby Letter of Credit Facilities
Secured letter of credit and trust arrangements were collateralized by pledged assets and assets in trust	$ 47,800,000		$ 57,700,000
Other Secured Letter of Credit and Trust Arrangement | Sirius Bermuda Insurance Company Ltd.
Standby Letter of Credit Facilities
Secured letter of credit and trust arrangements were collateralized by pledged assets and assets in trust	513,800,000		784,000,000
Sirius International | Nordea Bank Finland Abp
Standby Letter of Credit Facilities
Borrowing capacity					$ 90,000,000
Sirius International | DNB Bank ASA London Branch
Standby Letter of Credit Facilities
Borrowing capacity					35,000,000
Sirius International | Standby Letters of Credit
Standby Letter of Credit Facilities
Borrowing capacity					125,000,000
Sirius International | Unsecured Standby Letters of Credit | DNB Bank ASA London Branch
Standby Letter of Credit Facilities
Borrowing capacity					$ 25,000,000
Sirius International | Other Secured Letter of Credit and Trust Arrangement
Standby Letter of Credit Facilities
Secured letter of credit and trust arrangements were collateralized by pledged assets and assets in trust	$ 335,600,000	kr 3.4	$ 363,300,000	kr 3.4

Debt and standby letters of c_6

Debt and standby letters of credit facilities - Revolving Credit Facility (Details) - USD ($)	1 Months Ended
	Feb. 28, 2018	Mar. 31, 2020
Line of Credit Facility [Line Items]
Outstanding amount		$ 0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, term	3 years
Borrowing capacity	$ 300,000,000

Debt and standby letters of c_7

Debt and standby letters of credit facilities - Interest (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Debt Disclosure [Abstract]
Interest expense on debt	$ 7.8	$ 7.6
Total interest paid	$ 2.8	$ 2.7

Income taxes (Details)

Income taxes (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ (14,800,000)	$ 17,200,000
Pre-tax income (loss)	$ (136,100,000)	$ 121,300,000
Effective tax rate (as a percent)	10.90%	14.20%
Statutory tax rate (as a percent)	21.40%	21.40%
Tax Cuts and Jobs Act of 2017, BEAT tax rate, 2019-2025 (as a percent)	10.00%
Tax Cuts and Jobs Act of 2017, BEAT tax rate, 2026 and thereafter (as a percent)	12.50%
Provision for income taxes related to BEAT	$ 0		$ 0
Provision for income taxes related to GILTI	$ 0		$ 0

Income taxes - Deferred tax ass

Income taxes - Deferred tax asset, net of valuation allowance and Uncertain tax positions (Details) $ in Millions	Mar. 31, 2020USD ($)
Income taxes
Net deferred tax liability, net of valuation allowance	$ 12.5
Other net deferred tax liabilities	10.2
Uncertain tax positions
Total reserve for unrecognized tax benefits	42.8
Reversal of reserves for unrecognized tax benefits on permanent differences and interest and penalties	42.6
Reversal of reserves for unrecognized tax benefits on temporary differences	0.2
U.S. subsidiaries
Income taxes
Net deferred tax assets	27
Luxembourg subsidiaries
Income taxes
Net deferred tax assets	133
Sweden subsidiaries
Income taxes
Net deferred tax assets	182.7
Swedish Tax Authority | Sweden subsidiaries
Uncertain tax positions
Reserve attributable to uncertain tax positions	$ 42

Derivatives - Interest rate cap

Derivatives - Interest rate cap (Details) - Interest rate cap $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)financial_institution	Dec. 31, 2019USD ($)
Derivatives
Number of financial institutions entered into derivative contracts | financial_institution	2
Derivatives not designated as hedging instruments
Derivatives
Collateral balances held | $	$ 0.2	$ 0.2

Derivatives - Classification an

Derivatives - Classification and fair value of derivatives in consolidated balance sheets (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivatives
Derivative assets	$ 11.7	$ 11.4
Derivative liabilities	20.4	9.5
Interest rate cap | Derivatives not designated as hedging instruments
Derivatives
Notional Value	250	250
Interest rate cap | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	0	0
Interest rate cap | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	0	0
Foreign currency swaps | Derivatives not designated as hedging instruments
Derivatives
Notional Value	90	90
Foreign currency swaps | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	2.4	0
Foreign currency swaps | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	0	3.6
Foreign currency forwards | Derivatives not designated as hedging instruments
Derivatives
Notional Value	(215.2)	(30)
Foreign currency forwards | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	7.3	2.7
Foreign currency forwards | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	5.7	5.7
Weather derivatives | Derivatives not designated as hedging instruments
Derivatives
Notional Value	105.9	110.7
Weather derivatives | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	0	7
Weather derivatives | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	13.9	0
Equity futures contracts | Derivatives not designated as hedging instruments
Derivatives
Notional Value	20.1	34.5
Equity futures contracts | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	0	0
Equity futures contracts | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	0	0
Equity call options | Derivatives not designated as hedging instruments
Derivatives
Notional Value	1.9	0
Equity call options | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	0.1	0
Equity call options | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	0	0
Equity put options | Derivatives not designated as hedging instruments
Derivatives
Notional Value	11.4	31
Equity put options | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	1	1.3
Equity put options | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	0.8	0.2
Equity warrants | Derivatives not designated as hedging instruments
Derivatives
Notional Value	0.9	0.4
Equity warrants | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative assets	0.9	0.4
Equity warrants | Derivatives not designated as hedging instruments | Other liabilities
Derivatives
Derivative liabilities	$ 0	$ 0

Derivatives - Classification _2

Derivatives - Classification and fair value of derivatives in consolidated of (loss) income statements (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Interest rate cap | Other revenues
Derivatives
Gains (losses) recognized in earnings	$ 0	$ (0.1)
Foreign currency swaps | Net foreign exchange gains (losses)
Derivatives
Gains (losses) recognized in earnings	6	0.8
Foreign currency forwards | Net foreign exchange gains (losses)
Derivatives
Gains (losses) recognized in earnings	0.5	0.2
Weather derivatives | Other revenues
Derivatives
Gains (losses) recognized in earnings	(20.4)	(6)
Equity futures contracts | Net realized investment gains (losses)
Derivatives
Gains (losses) recognized in earnings	2.9	(0.6)
Equity futures contracts | Net unrealized investment gains
Derivatives
Gains (losses) recognized in earnings	(1)	(0.2)
Equity put options | Net realized investment gains (losses)
Derivatives
Gains (losses) recognized in earnings	5.5	0
Equity put options | Net unrealized investment gains
Derivatives
Gains (losses) recognized in earnings	0.5	(0.4)
Equity warrants | Net unrealized investment gains
Derivatives
Gains (losses) recognized in earnings	$ 0.5	$ 0

Share-based compensation - Narr

Share-based compensation - Narrative (Details) - USD ($) $ in Millions	Mar. 15, 2020	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 1.2	$ 0.2
Amount paid to employees for share-based awards		$ 0.3	3.3
Unrecognized share-based compensation costs			$ 34.3
Options granted in the period (in shares)		0	1,374,945
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average recognition period (years)			2 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average recognition period (years)			3 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average recognition period (years)		1 year 7 months 30 days
Awards granted in the period (in shares)		0	1,411,714
Retention Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted under the retention program	$ 13.8
Amount paid for retention awards	$ 6.9
Retention program expense		$ 6.3
Long Term Incentive Plan 2019 | Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average recognition period (years)		1 year 9 months
Awards granted in the period (in shares)		0	401,311
Long Term Incentive Plan 2020 | Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 1.6
Award vesting period				3 years

Share-based compensation - Unre

Share-based compensation - Unrecognized Compensation Cost and Period Of Recognition (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards	$ 9.8
Weighted average recognition period (years)	1 year 7 months 30 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards	$ 1.8
Weighted average recognition period (years)	1 year 11 months 12 days
IPO Incentive Awards | Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards	$ 2.6
Weighted average recognition period (years)	1 year 9 months
Long Term Incentive Plan 2019 | Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards	$ 1.1
Weighted average recognition period (years)	1 year 9 months
2018 Long Term Incentive Plan (LTIP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested awards	$ 0.2
Weighted average recognition period (years)	9 months

Share-based compensation - Unve

Share-based compensation - Unvested Share-based Awards Activity (Details) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Unvested, beginning of the year (in shares)	1,374,945
Granted (in shares)	0	1,374,945
Vested (in shares)	0
Forfeited (in shares)	0
Unvested, end of the year (in shares)	1,374,945
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning of the year (in shares)	1,353,852
Granted (in shares)	0	1,411,714
Vested (in shares)	0
Forfeited (in shares)	33,015
Unvested, end of the year (in shares)	1,320,837
IPO Incentive Awards | Performance share units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning of the year (in shares)	555,163
Granted (in shares)	0
Vested (in shares)	0
Forfeited (in shares)	11,967
Unvested, end of the year (in shares)	543,196
Long Term Incentive Plan 2019 | Performance share units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning of the year (in shares)	391,136
Granted (in shares)	0	401,311
Vested (in shares)	0
Forfeited (in shares)	8,809
Unvested, end of the year (in shares)	382,327
2018 Long Term Incentive Plan (LTIP)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning of the year (in shares)	870,471
Granted (in shares)	0
Vested (in shares)	0
Forfeited (in shares)	14,372
Unvested, end of the year (in shares)	856,099

Common shareholder's equity, _3

Common shareholder's equity, mezzanine equity, and non controlling interests - Common shareholder's equity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Common shareholder's equity
Common shares authorized (in shares)	500,000,000
Common shares par value (in usd per share)	$ 0.01
Preference shares authorized / designated ( in shares)	100,000,000
Preference shares par value (usd per share)	$ 0.01
Changes in common shareholders' equity
Shares issued, beginning of period (in shares)	115,299,341	115,151,251
Shares outstanding, beginning of period (in shares)	115,299,341	115,151,251
Issuance of shares to directors and employees (in shares)	0	111,052
Shares issued, end of period (in shares)	115,299,341	115,262,303
Shares outstanding, end of period (in shares)	115,299,341	115,262,303

Common shareholder's equity, _4

Common shareholder's equity, mezzanine equity, and non controlling interests - Mezzanine equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Nov. 05, 2018
Mezzanine equity
Preference shares authorized / designated ( in shares)	100,000,000
Preference shares par value (usd per share)	$ 0.01
Carrying value of preference shares	$ 199.6	$ 223
Series B preference shares
Mezzanine equity
Preference shares authorized / designated ( in shares)			15,000,000
Preference shares par value (usd per share)			$ 0.01
Preferential rights, aggregate gross proceeds from the issuance of senior or pari passu shares	$ 100
Series B preference shares | Sirius Group Private Placement | Preference Share Investors
Mezzanine equity
Share subscriptions (in shares)			11,901,670

Common shareholder's equity, _5

Common shareholder's equity, mezzanine equity, and non controlling interests - Non-controlling interests (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Change in non-controlling interest
Non-controlling interests, beginning of the period	$ 2.4	$ 1.7
Net income attributable to non-controlling interests	0.2	0.4
Other, net	0	0.1
Non-controlling interests, end of the period	2.6	$ 2.2
Alstead Re
Change in non-controlling interest
Non-controlling interests, beginning of the period	2.3
Non-controlling interests, end of the period	$ 2.5

Earnings per share - Basic and

Earnings per share - Basic and Diluted earnings per share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net (loss) income	$ (121.3)	$ 104.1
Less: Income attributable to non-controlling interests	(0.2)	(0.4)
Less: Change in carrying value of Series B preference shares	23.4	(8.4)
Net (loss) income attributable to Sirius Group's common shareholders	(98.1)	95.3
Less: Earnings attributable to Series B preference shares	0	(8.9)
Net income available to Sirius Group common shareholders	(98.1)	86.4
Add: Change in carrying value of Series B preference shares	(23.4)	8.4
Net income available to Sirius Group common shareholders on a diluted basis	$ (121.5)	$ 94.8
Denominator:
Weighted average shares outstanding for basic earnings per share (in shares)	115,262,302	115,182,331
Add: Series B preference shares (in shares)	11,901,670	11,901,670
Add: Unvested performance share units and restricted share units (in shares)	0	251,313
Weighted average shares outstanding for diluted earnings per share (in shares)	127,163,972	127,335,314
Earnings per share
Basic earnings per share (in usd per share)	$ (0.85)	$ 0.75
Diluted earnings per share (in usd per share)	$ (0.96)	$ 0.74
Potentially dilutive securities excluded from the calculation of Diluted earnings per share (in shares)	15,972,398	19,510,830

Investments in unconsolidated_3

Investments in unconsolidated entities - Other long-term investments (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Investments in unconsolidated entities
Other long-term investments	$ 355,500,000	$ 346,800,000
Equity method investments	0	0
Investments in unconsolidated entities
Investments in unconsolidated entities
Other long-term investments	355,500,000	346,800,000
Investments in unconsolidated entities | Equity method eligible investments
Investments in unconsolidated entities
Other long-term investments	151,800,000	151,900,000
Investments in unconsolidated entities | Equity method ineligible investments
Investments in unconsolidated entities
Other long-term investments	$ 203,700,000	$ 194,900,000

Investments in unconsolidated_4

Investments in unconsolidated entities - Equity method unconsolidated entities (Details) - Investments in unconsolidated entities - Equity method eligible investments	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
BE Reinsurance Limited
Investments in unconsolidated entities
Ownership interest	24.90%	24.90%
BioVentures Investors (Offshore) IV LP
Investments in unconsolidated entities
Ownership interest	73.00%	73.00%
Camden Partners Strategic Fund V (Cayman), LP
Investments in unconsolidated entities
Ownership interest	39.40%	39.40%
Diamond LS I LP
Investments in unconsolidated entities
Ownership interest	16.00%	16.00%
Gateway Fund LP
Investments in unconsolidated entities
Ownership interest	19.30%	15.00%
Monarch
Investments in unconsolidated entities
Ownership interest	12.80%	12.80%
New Energy Capital Infrastructure Credit Fund LP
Investments in unconsolidated entities
Ownership interest	30.50%	30.50%
New Energy Capital Infrastructure Offshore Credit Fund LP
Investments in unconsolidated entities
Ownership interest	30.50%	30.50%
Pie Preferred Stock
Investments in unconsolidated entities
Ownership interest	30.10%	30.10%
Pie Series B Preferred Stock
Investments in unconsolidated entities
Ownership interest	22.40%	22.40%
Quintana Energy Partners
Investments in unconsolidated entities
Ownership interest	21.80%	21.80%
Tuckerman Capital V LP
Investments in unconsolidated entities
Ownership interest	48.30%	48.30%
Tuckerman Capital V Co-Investment I LP
Investments in unconsolidated entities
Ownership interest	48.30%	48.10%

Variable interest entities (Det

Variable interest entities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Assets:
Fixed maturity investments	$ 1,732.1	$ 1,681
Short-term investments	1,041.8	1,085.2
Cash	140.5	136.3
Insurance and reinsurance premiums receivable	964.2	730.1
Funds held by ceding companies	260.5	293.9
Deferred acquisition costs	168.2	148.2
Other assets	143.7	161.4
Total assets	6,757.6	6,413.8
Liabilities
Loss and loss adjustment expense reserves	2,519.6	2,331.5	$ 1,976.3	$ 2,016.7
Unearned insurance and reinsurance premiums	979.2	708
Other liabilities	200.4	201.3
Total liabilities	5,081.3	4,548
VIEs
Assets:
Fixed maturity investments	3.6	3.9
Short-term investments	0.5	0.5
Cash	0.1	0.1
Total investments	4.2	4.5
Insurance and reinsurance premiums receivable	(0.5)	(0.3)
Funds held by ceding companies	3.4	3.4
Deferred acquisition costs	0.1	0.3
Other assets	0	0
Total assets	7.2	7.9
Liabilities
Loss and loss adjustment expense reserves	0.4	0.5
Unearned insurance and reinsurance premiums	0.1	0.6
Other liabilities	0.1	0.1
Total liabilities	$ 0.6	$ 1.2

Variable interest entities - Un

Variable interest entities - Unconsolidated VIE (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Variable interest entities
Other long-term investments	$ 355.5	$ 346.8
Total assets	6,757.6	6,413.8
Unconsolidated VIE
Variable interest entities
Other long-term investments	250.7	257.8
Total assets	250.7	257.8
On-Balance Sheet
Variable interest entities
Other long term investments	103	102.6
Total assets	103	102.6
Off-Balance Sheet
Variable interest entities
Other long term investments	8.8	16.3
Total assets	8.8	16.3
Other long-term investments
Variable interest entities
Other long term investments	111.8	118.9
Total assets	$ 111.8	$ 118.9

Transactions with related par_2

Transactions with related parties (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Transactions with related parties
Gross written premiums	$ 817.6	$ 622.3
Receivables due from affiliates	31		$ 16.1
Payables due to affiliates	0.9		$ 0.9
Insurance and MGU affiliates, or their subsidiaries
Transactions with related parties
Gross written premiums	$ 41.3	$ 24.1

Commitments and contingencies -

Commitments and contingencies - Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Leases
Operating lease expense	$ 3	$ 2.6
Operating lease right-of-use assets	26.1		$ 27.4
Lease liability	$ 27.8		$ 29.3
Leased offices
Leases
Weighted average lease term (years)	7 years
Leased equipment
Leases
Weighted average lease term (years)	3 years

Commitments and contingencies_2

Commitments and contingencies - Lease balances (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating lease right-of-use assets	$ 26.1	$ 27.4
Current lease liabilities	7.6	8.3
Non-current lease liabilities	$ 20.2	$ 21

Commitments and contingencies_3

Commitments and contingencies - Weighted average remaining lease term and weighted average discount rate (Details)	Mar. 31, 2020
Leased offices
Property, Plant and Equipment [Line Items]
Weighted average lease term (years)	7 years
Weighted average discount rate:	3.60%
Leased equipment
Property, Plant and Equipment [Line Items]
Weighted average lease term (years)	3 years
Weighted average discount rate:	3.40%

Commitments and contingencies_4

Commitments and contingencies - Future annual minimum rental payments (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
2020	$ 6.5
2021	8.1
2022	7.2
2023	4.7
2024	2.3
2025 and after	1.1
Total future annual minimum rental payments as at March 31, 2020	29.9
Less: present value discount	(2.1)
Lease liability	$ 27.8	$ 29.3

Uncategorized Items - sg-202003

Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (6,800,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	$ 771,700,000